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INDUSTRIAL     CHEMISTRY 

BEING   A    SERIES   OF   VOLUMES   GIVING   A 
COMPREHENSIVE   SURVEY   OF 

THE    CHEMICAL    INDUSTRIES 

EDITED  BY  SAMUEL  RIDEAL,  D.Sc.  LOND.,  F.I.C. 

FELLOW  OF   UNIVERSITY   COLLEGE,    LONDON 


ASSISTED  BY 

JAMES  A.  AUDLEY,  B.Sc.,  F.I.C.  ARTHUR  E.  PRATT,  B.Sc. 

W.  BACON,  B.Sc.,  F.I.C.,  F.C.S.  Assoc.  R.M.S. 

E.  DE  BARRY  BARNETT,  B.Sc.,   A.I.C.  ERIC  K.  RIDEAL,  M.A.,  PH.D., 
M.  BARROWCLIFF,  F.I.C.  F.I.C. 

H.  GARNER  BENNETT,  M.Sc.  W.  H.  SIMMONS,  B.Sc.,  F.I.C. 

F.  H.  CARR,  F.I.C.  -  R.  W.  SINDALL,  F.C.S. 
S.  HOARE  COLLINS,  M.Sc.,  F.I.C.  HUGH  S.  TAYLOR,  D.Sc. 
H.  C.  GREENWOOD,  O.B.E.,  D.Sc.,  F.I.C.  A.  DE  WAELE,  B.Sc.,  A.I.C. 
JAMES  KEWLEY,  M.A.,  F.I.C.,  F.C.S.  C.   M.  WHITTAKER,  B.Sc. 
J.  R.  PARTINGTON,  M.A.,  PH.D.  &c.,  &c. 


THE   PETROLEUM  AND 
ALLIED   INDUSTRIES 

PETROLEUM,  NATURAL  GAS,  NATURAL  WAXES, 

ASPHALTS   AND   ALLIED   SUBSTANCES, 

AND   SHALE   OILS 


BY 

JAMES    KEWLEY,  M.A.  (Cantab.),  F.I.C.,  F.C.S. 


NEW  YORK 

D.    VAN    NOSTRAND    COMPANY 

EIGHT  WARREN   STREET 

1922 


PRINTED   IN   GREAT   BRITAIN 


PREFACE 

THE  important  part  played  by  many  petroleum  products, 
notably  motor  spirits  and  liquid  fuels,  during  the  great  war, 
the  phenomenal  growth  of  motor  transport,  and  the  develop- 
ment of  aviation  have  directed  the  attention  of  a  large 
section  of  the  community  to  the  petroleum  industry.  The 
development  of  the  oilfields  of  the  British  Empire  and  the 
question  of  home  supplies  of  liquid  fuel  have  become  matters 
of  national  importance.  The  possibilities  of  augmenting 
petroleum  supplies  or  of  partially  replacing  them  by  means 
of  oils  derived  from  the  distillation  of  oil  shales  and  even 
of  coals,  are  receiving  serious  attention. 

This  great  industry  employs  a  multitude  of  men  a  large 
porportion  of  whom  are  necessarily  engaged  in  non- technical 
work.  Among  these  men  there  exists  a  very  commendable 
desire  to  know  something  of  the  great  industry  with  which 
they  are  associated,  a  desire  which  is  shared  by  many 
others  whose  connection  with  the  industry  is  indirect. 
This  book  has  been  written  in  the  hope  that  it  will  appeal 
to  such,  and  to  many  university  graduates  to  whom  a 
knowledge  of  the  outlines  of  an  industry  may  be  of 
assistance  in  determining  their  choice  of  a  career. 

An  effort  has  been  made  to  make  the  book  up  to  date 
as  far  as  possible,  and  to  include  not  only  crude  petroleum 
and  its  products  but  also  some  account  of  the  closely  related 
subjects,  such  as  natural  gas,  the  naturally  occurring  bitu- 
minous substances,  the  pyrobitumens  and  oil  shales.  The 
author  wishes  to  express  his  thanks  to  Dr.  H.  G.  Colman, 
Mr.  J.  E.  Hackford  and  Dr.  S.  Rideal  for  valuable 
suggestions  and  advice ;  also  to  acknowledge  his  indebted- 


vi  PREFACE 

ness  to  the  many  excellent  bulletins  published  by  the 
United  States  Bureau  of  Mines  and  other  departments,  to 
the  standard  works  to  which  reference  is  made  in  the 
text,  and  finally  to  the  Oil  Well  Supply  Co.,  the  Power 
Specialty  Co.,  Messrs.  Watts,  Fincham  &  Co.,  the  Sharpies 
Centrifugal  Co.,  and  the  Lucey  Manufacturing  Corporation 
for  their  kind  assistance  in  the  preparation  of  diagrams. 

J.  K. 

LONDON, 

June,  1922. 


CONTENTS 


PAGE 
PREFACE  v 


PART   I.— INTRODUCTORY 

SECTION  A. — TERMINOLOGY, 

Glossary  of  petroleum  products         .          .          .  -      •          .          .         .         I 

SECTION  B.— HISTORY. 

Early  history,  origin  of  shale-oil  industry,  origin  of  petroleum  refining 
industry,  development  of  coal-coking  industry,  scope  of  petroleum 
industry  and  its  possibilities .  .  .  6 

SECTION  C. — CHEMISTRY. 

Difficulties  of  petroleum  chemistry,  physical  methods  of  separating 
hydrocarbons,  chemical  methods  of  separation,  hydrocarbons  of  various 
classes  and  their  products,  sulphur,  nitrogen,  oxygen,  helium  .  .  14 

SECTION  D. — GEOLOGY. 

Geological  distribution,  modes  of  occurrence,  conditions  of  accumulation, 
types  of  oil-bearing  structure  .  .  ..  .  .  .  •  3* 

SECTION  E. — THEORIES  OF  ORIGIN. 

Inorganic  theory,  theories  as  to  animal  and  vegetable  origin,  possible 
relation  of  petroleum  to  coal  ........  38 


PART   II.— NATURAL  GAS 

SECTION  A.— OCCURRENCE,  DISTRIBUTION,  AND  COMPOSITION. 

Incredible  waste  of  gas,  production,  occurrence  underground,  capacity 

of  gas  wells,  composition         ........       43 

SECTION  B. — APPLICATIONS. 

Use  for  heating,  manufacture  of  carbon  black,  extraction  of  gasoline  by 
compression  and  absorption  processes,  helium    .....       49 

vii 


viii  CONTENTS 

PART   III.— CRUDE   PETROLEUM 

PAGE 

SECTION  A. — OCCURRENCE,  DISTRIBUTION,  AND  CHARACTER. 

General  considerations,  chief  types  of  crude  oils,  the  chief  oilfields  of 

the  world  and  the  character  of  their  oils,  output  of  crude  oil        .          .       60 

SECTION  B. — DRILLING  AND  MINING  OPERATIONS. 

Core  drill  methods,  percussion  methods,  derricks,  drilling  tools, 
spudding,  drilling,  casing,  shutting  off  water,  rotary  methods,  fishing 
operations,  flowing  wells,  methods  of  raising  oil,  pumping,  airlift, 
baling,  swabbing,  fires,  and  oilfield  waste  .....  69 

SECTION  C.— STORAGE  AND  TRANSPORT  OF  CRUDE  OIL  AND  ITS  LIQUID 
PRODUCTS. 
Tanks,  storage  losses,  pipelines,  tank  steamers  .....       85 

SECTION  D. — THE  DEHYDRATION  OF  CRUDE  OILS  ON  THE  FIELDS. 

Centrifugal  methods,  electric  methods,  distillation  methods          .          .       93 

PART  IV.— CRUDE  OILS  PRODUCED  BY  THE 
DISTILLATION  OF  SHALES,  COALS,  LIGNITES, 
AND  THE  LIKE 

SECTION  A.— CHARACTERS  AND  DISTRIBUTION  OF  OIL  SHALE. 

Oil  shales  contrasted  with  oil  sands,  kerogen,  ultimate  analyses,  origin 

of  oil  shales,  yield  of  oil,  geographical  distribution    .  .       97 

SECTION  B. — MINING  OF  SHALES .106 

SECTION  C. — LABORATORY  EXAMINATION  OF  OIL  SHALES  .  .     108 

SECTION  D. — RETORTING  OF  OIL  SHALES. 

Chemical  changes  consequent  on  retorting,  effect  of  steaming,  design 

of  retorts,  types  of  retorts        ...  .     1 1 1 

SECTION  E. — CHARACTERS  OF  SHALE  OILS. 

Presence  of  unsaturated  hydrocarbons,  comparison  with  petroleum  oils, 
relation  to  conditions  of  retorting  .  .120 

SECTION  F. — VARIOUS  TARS. 

Characters  of  various  tars  as  compared  with  petroleum  oils,  tars  as 
fuel  oils,  lignite  industry  in  Germany,  peat  .  .  -125 

PART   V.— NATURAL   SOLID   AND   SEMI-SOLID 
BITUMENS   AND   ALLIED   SUBSTANCES 

SECTION  A. — OCCURRENCE,  CHARACTERS,  AND  PRODUCTION. 

Asphalts  proper,  Bermudez,  Trinidad,  asphalt  rock,  asphaltites, 
gilsonite,  grahamite,  glance  pitch,  asphaltic  pyrobitumens,  elaterite, 
wurtzilite,  albertite,  impsonite  .....  .13° 

SECTION  B.— APPLICATIONS. 

Rock  asphalt  paving,  road  making  with  asphalts,  other  applications     .142 


CONTENTS  ix 

PART   VI.— THE   NATURAL   MINERAL   WAXES 

PAGE 

Ozokerite  and  ceresin,  montan  wax  .......     148 

PART  VII.— THE  WORKING  UP  OF  CRUDE  OILS 

SECTION  A. — DISTILLATION  OF  CRUDE  OIL. 

Periodic  distillation  at  atmospheric  pressure,  types  of  stills,  condensers, 
method  of  distillation,  use  of  de phlegm ators,  continuous  distillation, 
heat  exchangers  and  preheaters,  distillate  preheaters,  distillation  under 
high  vacuum,  distillation  in  tubular  stills,  Trumble  system,  efficiency 
of  distillation  plant  .  ,  .  .  .  .  .  .  .153 

SECTION  B. — REDISTILLATION  AND  FRACTIONATION  OF  LIGHT  OILS. 

Steam  stills,  fractionating  columns .188 

SECTION  C.— THE  CHEMICAL  TREATMENT  OF  PETROLEUM  AND  SHALE 
OILS. 

Treatment  with  sulphuric  acid,  types  of  agitators,  desulphurizing 
methods,  action  of  decolorizing  powders,  the  Edeleanu  process  .  .197 


SECTION  D. — THE  MANUFACTURE  OF  PARAFFIN  WAX   AND   LUBRI- 
CATING OIL. 

Chilling  of  Wax  distillates,  types  of  chillers,  filtration,  sweating  pro- 
cess, refining  of  wax,  residual  and  distilled  lubricating  oils,  refining 
of  lubricating  oils,  working  up  of  shale  oils,  medicinal  oils,  petro- 
latums, greases,  and  cutting  oils  .  ...  .  .  .  208 


SECTION  E. — THE  MANUFACTURE  OF  FUEL  OILS,  RESIDUAL  OILS  AND 
ASPHALTS  FROM  CRUDE  PETROLEUM. 

Distilled   fuel   oils  or  gas  oils,   residual   fuel    oils,    asphalts,    blown 
asphalts,  and  vulcanized  asphalts      .......     224 


SECTION  F. — CRACKING  AND  HYDROGENATION  PROCESSES. 

History  of  cracking,  nature  of  reactions,  methods  of  cracking,  processes 
of  Burton,  Hall,  Rittman,  etc.,  hydrogenation  methods,  various  other 
methods  .  .  .  229 


SECTION  G. — REFINERY  WASTE  PRODUCTS  :  THEIR  REGENERATION  AND 
UTILIZATION. 

Distillation  gases,  alcohols,  acid  sludge,  naphthenic  acids,  regeneration 

of  decolorizing  powders  .         .         .         .  .         .         •  237 


x  CONTENTS 

PART  VIII.— THE   CHARACTERS   AND   APPLICA- 
TIONS  OF   PETROLEUM   PRODUCTS 

SECTION  A. — BENZINES.  PAGE 

Special  benzines  for  extraction  purposes,  etc.,  benzines  as  motor  fuels, 
behaviour  of  various  types  of  hydrocarbons,  efficiency  of  motor  engines, 
interpretation  of  analytical  tests 241 

SECTION  B.— KEROSENES,  ILLUMINATING  OILS,  ETC. 

Characters  of  various  types  of  kerosenes,  interpretation  of  analytical 
tests,  kerosene  as  a  source  of  power 252 

SECTION  C. — GAS  OILS. 

Characters  and  specifications  of  gas  oils  :  their  use  as  fuels  for  internal 
combustion  motors,  gas  oils  for  gas  enriching  .....  257 

SECTION  D. — FUEL  OILS. 

Fuels  for  Diesel  engine  use,  characters  of  fuel  oils  and  tars  compared, 
methods  of  burning  fuel  oils,  advantages  over  coal  ....  262 

SECTION  E.— PARAFFIN  WAX. 

Various  uses  of  wax,  candles,  etc 268 

SECTION  F. — LUBRICATING  OILS. 

Characters  desired  in  lubricants,  types  of  lubricating  oils,  interpretation 

of  tests,  special  lubricant  and  transformer  oils    .         .         .         .         .271 

SECTION  G.— ASPHALTS. 

Asphalt  used  for  road  making,  roofing  felt,  weathering  of  asphalt, 
impregnated  fabrics,  mineral  rubber 281 


PART   IX.— THE  TESTING   OF   PETROLEUM 
PRODUCTS 

Need  for  standardization,  empirical  tests  for  boiling  point  range, 
viscosity  and  colour  and  comparative  data  for  various  types  of  instru  - 
ments 285 

SUBJECT  INDEX 297 

NAME  INDEX  299 


ABBREVIATIONS    USED    FOR    JOURNALS     REFERRED 
TO   IN   THE  TEXT 

J.I.P.T.— Journal  of  the  Institution  of  Petroleum  Technologists. 
J.S.C.I. — Journal  of  the  Society  of  Chemical  Industry. 
J.C.S. — Journal  of  the  Chemical  Society  of  London. 
J.R.S. A.— Journal  of  the  Royal  Society  of  Arts. 


PETROLEUM   AND   ALLIED 
INDUSTRIES 

PART   L— INTRODUCTORY 
SECTION  A.— TERMINOLOGY 

THE  terminology  of  petroleum  is,  unfortunately,  somewhat 
confused,  as  there  is  a  good  deal  of  ambiguity  and  over- 
lapping in  the  use  of  names.  This  is  due,  partly  to  the  use 
of  words,  sometimes  in  a  popular,  sometimes  in  a  scientific 
sense,  partly  to  the  meaning  of  many  words  having  been 
expanded  to  include  new  ideas,  and  partly  to  the  careless 
extension  of  the  use  of  words  to  include  meanings  which 
they  did  not  originally  convey.  Such  misuse  of  words  is 
only  too  common  in  other  industries,  e.g.  granite  is  often 
used  to  designate  such  different  rocks  as  marble  and  basalt. 
Although  there  is  at  present  no  standard  system  of  termin- 
ology in  use,  the  terms  as  used  in  this  book  will  bear  each 
a  definite  significance.  A  glossary  of  the  more  important 
terms  is  therefore  appended  : — 

Asphalts. — Solid  or  semi-solid  native  bitumens,  or  solid 
or  semi-solid  artificial  products  made  from  crude  petroleum. 
The  asphalts  are  relatively  easily  fusible.  This  term 
includes  also  those  native  bitumens  which  contain  a  con- 
siderable proportion  of  mineral  matter  as  well  as  those 
which  are  nearly  pure,  but  does  not  include  waxes. 

Asphaltenes.— Those  components  of  bitumens  which 
are  soluble  in  carbon  bisulphide  (benzol,  or  chloroform), 
but  insoluble  in  alcohol,  or  ether-alcohol  mixture. 

Asphaltites. — Native  bitumens,  relatively  difficultly 
P.  '  i 


2       PETROLEUM  AND  ALLIED  INDUSTRIES 

fusible,  largely  soluble  in  carbon  bisulphide  (gilsonite,  gra- 
hamite  and  the  glance  pitches).  They  are  composed  mostly 
of  asphaltenes  and  diasphaltenes. 

Asphaltic  Pyrobitumens. — Pyrobitumens  which  are 
infusible,  largely  insoluble  in  carbon  bisulphide,  and  relatively 
free  from  oxygenated  compounds. 

Astatki  (Ostatki). — A  Russian  term  designating  a 
petroleum  residual  fuel  oil. 

Benzine. — The  more  volatile  fractions  resulting  from  the 
distillation  of  petroleums,  shale  oils,  or  low-temperature 
tars,  up  to  the  point  at  which  the  distillates  merge  into 
kerosene  or  illuminating  oils.  This  term  includes  motor 
spirits,  petrols,  gasolines,  naphthas,  etc.,  which  terms  are 
all  synonymous  except  when  qualified.  Benzine  must  not 
be  confused  with  the  hydrocarbon  benzene  C6H6. 

Benzol. — The  volatile  or  low  boiling-point  distillates 
from  high-temperature  coal  tars,  composed  largely  of 
aromatic  hydrocarbons. 

Bitumen. — A  generic  term  covering  native  substances 
such  as  crude  petroleums,  natural  asphalts,  natural  waxes, 
the  non-mineral  constituents  of  which  are  largely  soluble  in 
carbon  bisulphide. 

Carbenes. — Those  constituents  of  bitumens  which  are 
soluble  in  carbon  bisulphide,  but  insoluble  in  carbon  tetra- 
chloride. 

Coal  Oil. — A  term  sometimes  used  in  America  to  include 
not  only  oil  obtained  by  the  distillation  of  coal  and  the 
illuminating  oils  obtained  therefrom,  but  also  illuminating 
oils  obtained  from  petroleum. 

Crude  Oil. — Naturally  occurring  liquid  bitumen. 

Diasphaltenes. — Those  portions  of  bitumens  which 
are  soluble  in  carbon  bisulphide,  and  in  ether,  but  insoluble 
in  ether-alcohol  mixture  (equal  parts) . 

Engine  Distillate. — A  product  intermediate  in  cha- 
racter between  benzine  and  kerosene. 

Gasoline. — Synonymous  with  motor  spirits,  petrol, 
naphtha,  or  benzine.  This  term  is  in  general  use  in 
America. 


TERMINOLOGY  3 

Goudron. — A  Russian  term,  meaning  a  petroleum  residue 
of  high  flash-point.  French  word  for  coal  tar. 

Kerites. — Natural  solid  asphaltic  pyrobitumens,  com- 
posed for  the  most  part  of  kerotenes  (e.g.  wurtzilite  and 
albertite). 

Keroles. — Those  portions  of  kerotenes  which  are 
soluble  in  pyridin  but  insoluble  in  chloroform. 

Kerols. — Those  portions  of  kerotenes  which  are  soluble 
in  pyridin  as  well  as  in  chloroform. 

Kerosene. — A  mixture  of  hydrocarbons  intermediate 
in  character  between  the  lighter  benzine  and  the  heavier 
gas-  or  solar-oil  fractions.  Kerosene  is  often  miscalled 
"  paraffin  oil "  in  the  British  Isles  and  "  coal  oil "  in  the 
United  States. 

Kerotenes. — Those  portions  of  bitumens,  asphaltic 
pyrobitumens  or  pyrobitumens  which  are  insoluble  in 
carbon  bisulphide. 

Liquid  Fuel. — A  term  usually  confined  to  heavy  (petro- 
leum) oils  of  flash-point  over  65°  C.  It  is  not  usually  taken 
to  include  motor  spirits,  although  this  certainly  might 
reasonably  be  expected. 

Malthenes. — Those  constituents  of  bitumen  (or  pyro- 
bitumen)  which  are  soluble  in  volatile  aromatic-free  petroleum 
spirits  (sp.  gr.  0-645). 

Mazout. — A  Tartar  word  synonymous  with  liquid  fuel. 

Naphtha. — A  word  very  loosely  used  to  include  volatile 
fractions  derived  both  from  petroleums  and  coal  tars.  Its 
use  will  be  avoided  in  this  work  except  in  connection  with 
coal-tar  products. 

Neutral  Oils. — A  term  used  in  America  to  denote  dis- 
tillates from  wax-  or  mixed-base  crudes,  containing  paraffin 
wax  and  lubricating  oils.  It  is  also  applied  to  the  lubri- 
cating oils  resulting  after  the  removal  of  the  wax  from  such 
distillates  by  chilling  and  filter  pressing. 

Ozokerite. — A  naturally  occurring  solid,  waxy  bitumen, 
often  known  as  earth  wax. 

Paraffin. — A  hydrocarbon  belonging  to  the  methane 
series. 


4        PETROLEUM  AND  ALLIED  INDUSTRIES 

Paraffin  Oil. — A  term  loosely  used  in  the  United 
Kingdom  to  designate  kerosene  or  illuminating  oils.  The  use 
of  this  word  paraffin  in  this  sense  should  be  avoided.  Also 
used  in  America  to  denote  lubricating  oils  made  by  dry 
distillation  of  certain  mixed-base  crude  petroleums.  The  use 
of  the  expression  will  be  avoided  in  this  work. 

Paraffin  Wax. — The  solid  waxes  produced  by  the 
distillation  of  crude  petroleums,  shale  or  other  oils. 

Petrol. — Popular  word  for  benzine  or  motor  spirits. 

Petroleum. — liquid  bitumen. 

Pitch. — The  solid  or  semi-solid  residue  obtained  from 
the  distillation  of  tars  derived  from  the  carbonization  of 
coal,  peat,  lignite,  resins,  woods,  etc.  It  should  not  be 
applied  to  the  solid  residues  derived  from  the  distillation  of 
bitumens. 

Pyrobitumens. — Solid,  infusible,  naturally  occurring 
bodies,  practically  insoluble  in  carbon  bisulphide,  derived 
from  the  metamorphosis  of  vegetable  matter  (lignites,  coals, 
anthracites),  or  of  asphalts  (e.g.  elaterite  and  albertite). 

Road  Oil. — A  trade  name  covering  types  of  oils,  varying 
from  those  used  for  spraying  roads  as  a  dust  preventive 
to  soft  asphalts. 

Stove  Distillate. — A  product  made  in  California,  inter- 
mediate in  character  between  kerosene  and  gas  oil. 

Tar. — A  liquid  derived  from  the  distillation  of  coal, 
lignite,  peat,  wood,  or  other  vegetable  substance.  It  is  not, 
in  this  book,  applied  to  any  bitumen  product. 

Wax  Tailings. — A  heavy  distillate  obtained  during  the 
final  stages  of  distilling  certain  mixed  base  oils  down  to 
coke.  This  product  contains  anthracene  and  chrysene 
produced  by  cracking. 

Practically  the  first  attempt  to  place  the  nomenclature 
of  petroleum  on  a  scientific  basis  has  recently  been  made  by 
J.  E.  Hackford,  in  a  paper  read  before  the  Institution  of 
Petroleum  Technologists  in  Februaiy,  1922. 

As  a  result  of  investigations  with  the  so-called  asphalt- 
ites,  asphaltic  and  non-asphaltic  pyrobitumens,  their  con- 
ditions of  occurrence  and  their  relation  to  the  crude  oils 


TERMINOLOGY  5 

from  which  they  have  been  derived,  supported  by  laboratory 
data  and  the  actual  experimental  transformation  of  one 
type  into  another,  he  has  been  able  to  put  forward  a  theory, 
by  means  of  which  these  bodies  can  be  correlated  and  thus 
scientifically  classified.  So  far,  only  the  outlines  of  the 
scheme  have  been  worked  out  and  much  work  remains  to  be 
done  before  the  conception  can  find  general  application.  It 
is  only  when  such  work  has  been  amplified  and  recognized 
that  any  scientific  nomenclature  for  crude  petroleums  and 
allied  products  can  be  evolved. 


SECTION  B.— HISTORY 

OF  the  industries  dealt  with  in  this  book,  that  of  petroleum 
is  at  the  present  day  of  outstanding  importance,  though 
really  yet  only  in  its  infancy  as  far  as  technical  development 
is  concerned.  That  of  shale  oil,  at  one  time  more  important, 
is  now,  owing  to  adverse  conditions,  in  a  state  of  arrested 
development.  The  growing  demand  for  oils  of  all  kinds,  and 
the  possibility  of  the  petroleum  industry  alone  being  unable 
in  the  future  to  meet  these  requirements  is,  however,  directing 
attention  anew  to  the  potentialities  of  oil  shale,  so  that  under 
favourable  conditions,  its  great  development  in  the  future 
may  be  perhaps  expected. 

The  allied  industry  of  the  low-temperature  carbonization 
of  coal  is,  at  present,  only  in  embryo.  It  is  receiving  much 
attention,  and  the  day  of  its  commercial  development  is 
probably  not  far  distant. 

The  origin  of  the  petroleum  industry  dates  back  to 
those  early  ages,  of  the  history  of  which  we  know  so 
little.  The  product  of  which  we  have  the  earliest  records 
is,  as  would  be  expected  from  its  non-volatile  nature, 
asphalt. 

This  was  used  about  3000  B.C.  by  the  Sumerians,  a  people 
skilled  in  sculpture,  who  inhabited  the  Euphrates  valley. 
Works  of  art  of  these  early  peoples,  now  reposing  in  museums, 
show  that  asphalt  was  used  as  a  basis  or  cement  for  inlaying 
mosaics.  It  seems  strange  that  the  resources  of  Mesopotamia, 
the  country  in  which  a  bitumen  was  first  used,  have  not  yet 
been  to  any  extent  developed.  The  early  Persians,  2500  B.C., 
used  asphalt  for  similar  purposes.  The  earliest  known 
Egyptian  mummies  were  encased  in  cloth  treated  with  a 
liquid  bitumen.  Nebuchadnezzar  constructed  a  high-road 

6 


HISTORY  7 

of  burnt  bricks  laid  in  asphalt,  the  precursor  of  the 
modern  pavement  of  stone  blocks,  grouted  in  with  pitch  or 
asphalt. 

It  is  interesting  to  note  in  this  connection  that  the  name 
asphalt  is  derived  from  the  Greek  ao-^aXrje,  signifying  secure 
or  firm. 

The  Bible  contains  many  references  to  crude  petroleum 
and  asphalt.  The  "  pitch  "  used  in  connection  with  the 
ark  was  undoubtedly  a  bitumen.  The  word  "  slime  "  used 
in  connection  with  the  Tower  of  Babel  and  elsewhere, 
undoubtedly  refers  to  asphalt.  Many  of  the  references  to 
oil,  e.g.  "  oil  out  of  the  flinty  rock,"  probably  refer  to  crude 
petroleum. 

For  more  than  2500  years  issues  of  natural  gas  on  the 
shores  of  the  Caspian  Sea  have  been  objects  of  religious 
reverence. 

Early  I,atin  and  Greek  writers  make  many  references, 
not  only  to  asphalts,  but  also  to  crude  oils  and  gas.  Pliny, 
for  example,  mentions  that  Sicilian  oil  was  burned  in  lamps 
in  the  Temple  of  Jupiter.  Herodotus,  in  450  B.C.,  described 
the  so-called  "pitch  spring"  of  Zante,  a  seepage  which 
exists  to  this  day. 

More  than  1000  years  ago  Yenangyaung  in  Burmah  was 
a  developed  oil-field.  The  Chinese  sunk  hand-dug  wells 
before  the  Christian  era,  ventilating  the  shafts  with  large 
bellows  with  their  usual  ingenuity.  They  also  used  natural 
gas  as  a  source  of  heat  for  evaporating  brine.  In  Japan, 
too,  the  industry  is  of  very  long  standing.  The  use  of 
petroleum  in  that  country  was  first  recorded  in  668  A.D., 
when  the  people  of  Echigo  provinces  brought  forward 
as  a  present  to  the  Emperor  a  marvellous  burning  water. 
In  1613,  Magara  found  oil  at  Niitsu,  and  actually 
distilled  it  from  a  vessel,  condensing  the  distillate,  which 
he  sold  as  an  illuminant.  This  is  probably  the  earliest 
instance  of  an  attempt  to  split  up  crude  oil  into  its  com- 
ponents. 

In  the  days  of  the  early  North  American  settlers  numerous 
oil  pits,  lined  with  roughly  hewn  balks  of  timber,  were 


8       PETROLEUM  AND  ALLIED  INDUSTRIES 

often  found  in  Pennsylvania.  These  were  certainly  of  great 
antiquity,  probably  constructed  by  the  "  Mound-builders," 
the  predecessors  of  the  present  race  of  Indians.  In  1535 
asphalt  was  discovered  in  Cuba  and  utilized  for  painting 
ships,  and  in  1595  Sir  Walter  Raleigh  first  described  the 
famous  Trinidad  Asphalt  I^ake,  which  has  since  afforded 
such  a  prolific  source  of  supply  of  asphalt  for  paving  pur- 
poses. In  the  early  part  of  the  nineteenth  century  oil  was 
often  found  in  wells  dug  for  brine,  in  the  north-eastern  States 
of  North  America,  its  presence  being,  however,  regarded  as  a 
nuisance. 

During  the  early  part  of  the  nineteenth  century  attempts 
were  made  to  produce  illuminating  oils  and  lubricants  by  the 
distillation  of  coals  and  shales.  As  far  back  as  1694  Hancock 
and  Portlock  took  out  an  English  patent  for  shale  tar  and 
pitch.  In  1746  Murdoch  laid  the  foundations  of  the  present 
coal-gas  industry,  and  in  1846  Gessner  manufactured  an 
illuminant  from  the  albertite  of  New  Brunswick,  calling  it 
kerosene.  (The  older  name  of  coal  oil,  however,  still  persists 
in  America  to  the  present  day.) 

In  1830  von  Reichenbach  isolated  paraffin  wax  from 
wood  tar,  and  gave  it  the  name  which  it  still  bears.  De  la 
Haye  and  I/aurent  produced  crude  shale  oil  about  the  same 
time,  and  worked  it  up  into  illuminants,  lubricating  oils  and 
wax,  thus  founding  an  industry  in  the  south  of  France,  which 
has  persisted  there  up  to  the  present  day.  Various  attempts> 
which  however  met  with  little  success,  were  made  about  the 
same  period  to  utilize  peat. 

The  work  of  James  Young  forms  a  landmark  in  the 
history  of  the  distillation  of  shales.  He  first  built  a  refinery 
for  the  treatment  of  the  crude  petroleum  which  was  found 
in  a  coal-mine  in  Alfreton,  in  Derbyshire,  and  made  lamp 
oils,  lubricants,  and  a  little  paraffin  wax  therefrom.  After 
a  year  or  two,  however,  the  flow  of  oil  ceased,  and  Young 
was  forced  to  look  out  for  other  sources  of  supply.  After 
examining  many  samples  he  eventually  hit  upon  the  Boghead 
coal  from  Torbanehill,  and  at  once  set  up  a  retorting  and 
distilling  plant,  thus  laying  the  foundation  of  the  Scottish 


HISTORY  9 

shale-oil  industry.  This  industry  enjoyed  years  of  prosperity 
before  the  keen  competition  of  the  more  cheaply  manu- 
factured petroleum  products  imported  from  America  caused 
it  to  decline.  In  1858  Riebeck  erected  the  first  important 
distillation  plant  in  Saxony  for  the  working  up  of  lignite, 
thereby  establishing  a  similar  industry,  which,  like  that  of 
the  Scotch  shale  oils,  still  exists. 

The  year  1859  marks  an  epoch  in  the  history  of  the 
petroleum  and  allied  industries.  In  that  year,  at  Titusville, 
Colonel  E.  I/.  Drake,  acting  for  the  Pennsylvania  Rock  Oil  Co., 
drilled  the  first  well  in  the  United  States,  really  bored  with 
the  intention  of  finding  oil.  Oil  was  struck  at  a  depth  of 
only  70  feet.  This  find  caused  great  excitement,  and 
Oil  Creek,  Titusville,  soon  developed  into  an  important 
oil  centre.  The  methods  of  distillation  and  refining  adopted 
by  Young  in  Scotland  were  modified  and  adapted  to  the 
requirements  of  the  new  industry,  and  from  that  time  onwards 
development  was  rapid.  The  new  industry  boomed.  New 
oil-fields  were  discovered,  and  developed  with  feverish 
activity.  Towns  sprang  up  almost  in  a  night,  and  rapidly 
disappeared  when  the  field  became  exhausted  or  proved  a 
failure. 

It  is  lamentable  to  think  that  Colonel  Drake  died  a  poor 
man.  Only  recently  indeed  have  his  services  to  the  industry 
been  appreciated.  A  simple  monument  now  stands  on  the 
site  of  his  first  well. 

The  developmentof  the  industry  in  the  United  States  iswell 
illustrated  by  the  following  figures,  giving  the  approximate 
quantities  of  petroleum  products  marketed  in  the  U.S.A. : — 

Tons. 

1859 300 

1860 70,000 

1865 357,00° 

1875 1,255,000 

1885 2,743,000 

1895 8,233,000 

1905 12,023,000 

1913 3 


io     PETROLEUM  AND  ALLIED  INDUSTRIES 

The  world's  production  in  1920  amounted  to  97,512,000 
tons  (metric). 

In  Russia  the  Baku  fields  were  worked  from  the  early 
part  of  the  nineteenth  century.  About  1872  the  annual 
production,  obtained  from  pit  wells,  had  reached  as  high  a 
figure  as  25,000  tons.  Five  years  later  the  output  was  nearly 
ten  times  as  large,  and  in  1901  it  had  attained  a  figure  of 
10,850,000  tons.  The  Apscheron  district  has  always  been 
characterized  by  large  gushers,  which  have,  however,  become 
smaller  and  less  frequent  owing  to  the  increasing  exhaustion 
of  the  fields.  The  industry  in  Galicia  dates  back  to  1854, 
and  in  Roumania  to  1866.  The  Burmah  oil  industry  began 
to  develop  about  1891,  and  that  of  the  Dutch  East  Indies 
about  the  same  time.  The  industries  in  Persia,  Egypt, 
Mexico,  Venezuela,  and  also  in  many  areas  in  the  United 
States  are  of  comparatively  recent  growth. 

While  the  petroleum  industry  of  North  America  was 
advancing  with  such  rapid  strides,  the  shale-oil  industry 
in  Scotland  was  fighting  its  way  against  adverse  conditions, 
the  relatively  cheap  imported  illuminating  oils  proving  serious 
competitors  to  the  home-produced  products.  From  1850 
to  1862  torbanite,  a  variety  of  cannel  coal,  which  yielded  as 
much  as  100  to  120  gallons  of  oil  per  ton,  was  worked,  but  as 
supplies  of  this  material  became  exhausted,  oil  shales  were 
substituted.  These  shales  yielded  much  less  oil,  20  to  50 
gallons  per  ton,  but  much  more  ammonia.  In  spite  of  the 
continually  diminishing  yields  of  crude  oil  given  by  the 
shales  lying  at  greater  depths,  and  subsequently  worked, 
the  industry  has  been  able  to  hold  its  own  owing  to  the 
increased  value  of  the  principal  by-products,  notably  the 
ammonium  sulphate.  The  progress  of  the  industry  in 
Scotland  has  been  marked  by  great  fluctuations.  At  various 
times,  during  its  early  days,  nearly  120  concerns  were 
operating.  In  1871  this  number  had  decreased  to  51,  in  1894 
to  13,  and  in  1906  to  only  6.  These  latter  have  now  been 
amalgamated  into  one  concern.  In  spite  of  the  reduction 
in  the  number  of  the  operating  companies,  the  output, 
however,  has  shown  a  steady  increase. 


HISTORY  ii 

Tons  output 
Year.  of  Scotch  Shale. 


1873  ..  .. 

1885  ..  ..  1,741,700 

1895  ........  2,236,200 

1917  ..     ..  ..  3,116,529 

1920  ........  2,763,875 

Considerable  development  in  the  coal  coking  industry  has 
taken  place  during  the  last  sixty  years.  In  the  early  'fifties 
of  the  nineteenth  century  Knab,  Hauport,  and  Carves 
developed  recovery  coke  ovens.  These  have  now  largely 
replaced  the  old  coke  ovens  of  the  beehive  type,  all  by- 
products from  which  were  invariably  completely  lost. 
Too  many  of  these  wasteful  plants  are,  however,  still  in 
operation  both  in  this  country  and  in  America.  It  is  high 
time  that  the  squandering  of  our  country's  resources  in  this 
disgraceful  fashion  was  brought  to  an  end.  In  1887  Brunck 
introduced  benzol  recovery,  a  process  which  is  now  generally 
applied  to  coke-oven  gases,  though  not  to  domestic  coal  gas. 

Attention  has  of  recent  years  also  been  paid  to  the  re- 
covery of  tars  from  blast-furnace  gases  and  producer  plants. 

The  low-temperature  carbonization  of  coal  and  the 
economic  utilization  of  low-grade  coals  are  questions  which 
have  not  yet  been  economically  solved.  They  are,  however, 
receiving  much  attention,  and  the  day  is  undoubtedly  not 
far  distant  when  the  scandalous  waste  of  these  low-grade 
fuels,  not  to  mention  the  inefficient  methods  of  utilization 
of  high-grade  coals,  will  no  longer  be  permitted. 

Concurrently  with  the  growth  of  the  petroleum  industry 
there  developed  a  considerable  expansion  in  the  number  of 
derivatives  and  by-products  and  their  applications.  The 
comparatively  recent  development  of  the  various  forms  of 
internal  combustion  motor  has  gone  hand-in-hand  with  the 
supply  of  suitable  fuels. 

Modern  printing  depends  largely  on  petroleum  natural  gas 
for  supplies  of  the  best  qualities  of  lamp-black  ;  the  electrical 
industries  absorb  large  quantities  of  paraffin  wax  and 
asphalts  ;  mineral  lubricating  oils  are  now  generally  used  to 


12     PETROLEUM  AND   ALLIED  INDUSTRIES 

the  almost  entire  exclusion  of  vegetable  oils,  which  are 
incidentally  more  valuable  for  edible  purposes  ;  and  modern 
roads,  in  order  to  cope  with  the  continual  increase  in  the 
number  of  heavier  and  more  rapid  vehicles,  depend  more  and 
more  upon  natural  asphalts  and  the  similar  artificial  petro- 
leum residues. 

The  recent  development  of  the  mineral  separation  process 
which  depends  on  the  fact  that  certain  minerals  adhere  to 
petroleum  oils  affords  an  interesting  example  of  a  modern 
application  of  petroleum  products.  The  extraction  of  helium 
in  large  quantities  from  natural  gas  during  the  last  few 
months  of  the  great  war,  is  surely  one  of  the  romances  of 
industrial  history. 

Of  recent  years,  changes  in  the  relative  values  of  products 
have  brought  about  corresponding  changes  in  the  methods 
of  working  up  crude  oils.  The  volatile  fractions,  which  are 
now  of  such  value  as  fuels  for  internal  combustion  motors, 
were  at  one  time  regarded  as  waste  products  and  were 
actually  sometimes  got  rid  of  by  burning.  Kerosenes,  in 
those  days,  were  made  so  as  to  contain  as  much  of  the  volatile 
fractions  as  the  minimum  legal  flashpoint  would  allow.  The 
position  now  is  completely  reversed,  the  problem  being  to 
include  as  much  as  possible  of  the  kerosene  light  fractions  in 
the  motor  spirit.  liquid  fuel,  at  one  time  a  drug  in  the 
market,  is  now  in  great  demand.  The  high  aromatic  content 
of  certain  crudes,  which  at  one  time  much  depreciated  their 
value,  now  renders  them  of  great  importance.  Such 
changes  are  naturally  only  to  be  expected  as  the  result  of 
research  and  development. 

The  petroleum  industry  is,  however,  still  only  partially 
developed.  The  comparative  ease  with  which  large  produc- 
tions have  been  obtained,  and  the  fact  that  the  bulk  of 
petroleum  products  have  been,  and  still  are,  used  for  fuel 
purposes,  are  factors  which  do  not  make  for  efficiency. 
Appalling  waste  has  until  recently  been  a  feature  of  oil- 
field development.  Inefficient  refining  methods  are  still 
largely  in  use.  The  fuel  consumptions  of  many  refineries 
are  still  far  too  high,  and  many  refining  processes  still  in  use 


HISTORY  13 

involve  large  refining  losses.  The  industry  presents,  there- 
fore, many  interesting  problems  ("The  Problems  of  the 
Petroleum  Industry,"  by  W.  A.  Hamor,  Chem.  and  Met. 
Eng.,  1920,  p.  425). 

The  extraction  of  crude  oil  from  its  subterranean  reser- 
voirs leaves  much  to  be  desired,  as  it  is  estimated  that  not 
much  more  than  30  per  cent,  of  the  underground  oil  is  ever 
brought  to  the  surface. 

The  ever-increasing  demand  for  volatile  liquid  fuels 
suitable  for  high-speed  internal  combustion  motors,  caused 
by  the  great  developments  in  motor  traction  must  before 
long  bring  about  a  shortage  of  the  volatile  petroleum 
fractions  at  present  almost  exclusively  used  for  this  purpose. 

Methods  of  converting  the  relatively  abundant  heavier 
oils  into  more  volatile  products  must  be  worked  out.  Many 
experimenters  are  indeed  at  work  on  this  problem  and  are 
attacking  it  mainly  from  two  directions,  viz. :  "  cracking  " 
and  "hydrogenation." 

So  far,  little  work  has  been  done  in  the  direction  of 
preparing  from  crude  petroleum,  products  other  than  the 
various  forms  of  fuels,  lubricating  oils,  waxes,  and  asphalts. 
Such  a  complex,  mixture  of  hydrocarbons  as  a  crude 
petroleum  must  surely  some  day  form  the  starting-point 
for  a  large  number  of  derivatives  or  by-products.  The 
work  now  being  done  in  the  direction  of  producing  fatty 
acids  by  the  oxidation  of  petroleum  oils  probably  fore- 
shadows such  a  development.  The  opportunities  for 
research  in  this  direction  are  great  indeed. 

GENERAL   REFERENCES   TO   PART   I.,    SECTION   B. 

Abraham,  "  Asphalts  and  Allied  Substances."  D.  van  Nostrand  Co., 
New  York. 

Ells,  "  The  Bituminous  Shales  of  New  Brunswick  and  Nova  Scotia." 
Canada  Dept.  of  Mines. 

Gesner,  "  Coal  Oils."     Bailliere  Bros.,  New  York.     1865. 

Henry,  "  History  and  Romance  of  the  Petroleum  Industry."  Bradbury, 
Agnew  and  Co.,  London. 

Pascoe,  "  Memoirs  of  Geological  Survey  of  India,"  vol.  40. 

Redwood,  "  Treatise  on  Petroleum,"  vol.  i.     C.  Griffin  and  Co. 

Ross,  "  Evolution  of  the  Oil  Industry."  Doubleday,  Page  and  Co., 
New  York. 

Scheithauer,  "  Shale  Oils  and  Tars."     Scott,  Greenwood  and  Son. 


SECTION  0.— CHEMISTRY 

IT  is  at  first  sight  surprising  to  find  that  so  little  is  really 
known  of  the  chemistry  of  petroleum  (and  shale  oil)  in  view 
of  the  enormous  importance  which  the  industry  has  now 
attained.  When,  however,  the  complexity  of  the  subject 
and  the  difficulties  of  investigation  are  taken  into  considera- 
tion, the  lack  of  knowledge,  although  deplorable,  is  readily 
understood.  The  same  may  be  said  of  the  chemistry  of 
coal,  and  of  its  distillation  products  under  various  conditions. 
This  subject  is  of  even  greater  importance,  as  the  supplies 
of  petroleum  are  limited,  the  end  of  many  great  producing 
fields  being  already  in  sight.  The  world's  supplies  of  shale 
and  coal  are  undoubtedly  far  greater  than  of  petroleum,  and 
in  years  to  come  the  shale  oil  and  coal  distillation  industries 
must  play  a  great  part. 

Crude  petroleums,  shale  oils,  and  tars,  are  composed 
mainly  of  hydrocarbons,  associated,  particularly  in  the  case 
of  tars,  with  varying  proportions  of  oxygen,  sulphur,  and 
nitrogen  derivatives. 

Owing  to  the  enormous  number  of  isomeric  hydrocarbons 
which  may  exist  when  the  molecule  contains  more  than 
5  or  6  carbon  atoms,  and  to  the  similarity  in  the  properties 
of  members  of  any  one  series,  the  isolation  and  investigation 
of  individual  hydrocarbons  from  crude  oils  present  very 
great  difficulties,  as  a  natural  consequence  of  which  the 
volatile  hydrocarbons  of  relatively  low  molecular  weight 
have  received  most  attention.  Many  of  these  have  been 
isolated  in  a  state  of  purity.  Several  of  the  lower  members, 
particularly  those  of  the  aromatic  series,  have  actually  been 
extracted  commercially  from  petroleum.  For  example, 
many  thousands  of  tons  of  trinitrotoluene  were  made  from 

14 


CHEMISTRY  15 

toluene  derived  from  a  Borneo  petroleum  during  the  recent 
war  (Kewley,  J.I.P.T.,  1921,  p.  209). 

A  further  difficulty  in  the  isolation  and  examination 
of  the  constituents  of  higher  boiling  points,  arises  from  the 
fact  that  chemical  changes  often  take  place  during  the  dis- 
tillation of  crude  petroleums,  even  at  temperatures  as  low 
as  200°  C.,  so  that  it  by  no  means  follows  that  components 
found  in  distillates  are  present  as  such  in  the  crude.  This 
is  unfortunate,  as  distillation  is  naturally  the  obvious  means 
of  effecting  some  sort  of  separation. 

Such  decomposition  or  "  cracking  "  as  it  is  termed,  finds, 
however,  a  technical  use,  being  applied  to  the  increasing  of 
the  output  of  light  fractions  (benzines)  from  certain  crudes 
(vide  Part  VII.,  Section  F). 

Recently,  however,  Krieble  and  Seyer  (J.  Am.  Chem. 
Soc.,  1921,  p.  1337)  have  shown  that  by  distilling  under 
really  high  vacuum,  as  low  as  O'i  mm.,  heavy  hydrocarbon 
oils  can  be  distilled  up  to  temperatures  as  high  as  300°  C. 
without  cracking. 

If  the  various  hydrocarbons  or  other  bodies  present 
could  only  be  separated  from  each  other  by  physical  means, 
other  than  distillation,  much  more  might  be  learned  of  their 
chemistry.  The  only  physical  means  which  at  present 
appear  to  be  available  are  : — 

(1)  Distillation  under  high  vacuum. 

(2)  The  differential  action  of  solvents. 

(3)  Diffusion. 

In  connection  with  the  first  it  may  be  mentioned  that 
paraffin  wax,  which  readily  cracks  on  distillation,  may  be 
easily  distilled  in  high  vacuum  without  any  appreciable 
change.  High-vacuum  distillation  is  technically  employed 
in  the  manufacture  of  the  best  qualities  of  lubricating 
oil,  in  order  to  avoid  decomposition  as  far  as  possible. 

An  example  of  the  second  method  is  afforded  by  Lessing's 
process  for  the  treatment  of  coal  tars  (Eng.  Pat.  130362  of 
1919).  When  such  a  tar  is  treated  with  benzine  containing 
no  aromatic  hydrocarbons,  it  is  split  up  into  a  pitch  which  is 
precipitated  out,  and  a  tar  oil  which  dissolves  in  the  spirit, 


16     PETROLEUM  AND  ALLIED  INDUSTRIES 

from  which  it  is  separated  by  distillation.  The  tar  and  oils 
so  obtained  are  somewhat  different  from  those  obtained  by 
distillation.  The  pitch  contains  much  less  insoluble  free 
carbon  than  does  that  resulting  from  ordinary  distillation 
treatment,  as  it  lacks  the  free  carbon  formed  by  decomposi- 
tion during  distillation,  and  the  tar  oils  also  differ  somewhat 
from  those  obtained  by  distillation.  It  is  evident  therefore 
that  considerable  changes  take  place  during  the  distillation 
of  coal  tar.  The  application  of  a  similar  method  (if  a  suitable 
solvent  were  found)  to  crude  oils  would  doubtless  lead  to 
interesting  results. 

A  further  application  of  this  method  is  afforded  by 
the  Edeleanu  process,  in  which  liquid  sulphur  dioxide  at  a 
low  temperature  is  used  for  the  removal  of  aromatic  and 
unsaturated  compounds  from  petroleum  distillates  (vide  Pt. 
VII.,  Sec.  C).  The  use  of  dimethyl  sulphate  (Valenta,  Chem. 
Ztg.,  1906,  p.  266)  has  been  advocated  for  the  separation  of 
aromatic  hydrocarbons,  but  its  use  has  limitations,  and  it  is, 
moreover,  objectionable  owing  to  its  exceedingly  poisonous 
nature.  Various  alcohol  mixtures  have  been  used  as 
differentiating  solvents  by  Charitschkoff  and  Wolochowitsch 
(Chem.  Ztg.,  1902,  p.  224),  carbon  tetrachloride  by  Graefe 
(Chem.  Rev.,  1906,  p.  30),  acetic  anhydride  and  alcohol  ether 
mixtures,  by  Zaloziecki.  A  method  of  estimation  of  paraffin 
wax  is  based  on  its  relative  insolubility  in  a  mixture  of 
alcohol  and  ether  at  low  temperatures  (Holde,  "Untersuchung 
der  Mineralole  und  Fette,"  3rd  edition,  p.  28). 

I<ittle  work  has  as  yet  been  done  on  the  lines  suggested 
by  method  (3),  Day  (Bulletin  365,  U.S.  Geol.  Survey), 
Gilpin  and  Bransky  (Amer.  Chem.  Journal,  vol.  44,  p.  251), 
Bngler  and  Albrecht  (Zeit.  angew.  Chem.,  1901,  p.  889)  have 
examined  the  behaviour  of  crude  oil  when  subjected  to  slow 
nitration  through  finely  divided  media,  such  as  fuller's- 
earth.  Day  made  the  following  observations :  "  (i)  when 
petroleum  is  allowed  to  rise  in  a  tube  packed  with  fuller's- 
earth,  there  is  a  decided  fractionation  of  the  oil,  the  fraction 
at  the  top  of  the  tube  being  of  lower  specific  gravity  than 
that  at  the  bottom.  (2)  When  water  is  added  to  fuller's- 


CHEMISTRY  17 

earth  which  contains  petroleum,  the  oil  which  is  displaced 
first  differs  in  specific  gravity  from  that  which  is  displaced 
afterwards,  when  more  water  is  added.  (3)  When  petroleum 
is  allowed  to  rise  in  a  tube  packed  with  fuller's-earth,  the 
paraffin  hydrocarbons  tend  to  collect  in  the  lightest  fraction 
at  the  top  of  the  tube  and  the  unsaturated  hydrocarbons 
at  the  bottom. 

This  filtration  process  on  a  natural  scale  is  undoubtedly 
responsible  for  the  occurrence  of  many  abnormal  crude  oils, 
the  so-called  white  oils  which  have  been  found  in  Russia, 
Canada,  and  elsewhere,  usually  in  small  quantities.  Indeed, 
many  crude  oils  have  undergone  such  a  filtration  to  some 
extent,  as  the  occurrence  of  oil  in  the  formation  in  which  it 
was  formed  (its  mother  rock)  is  unusual ;  migration  has  in 
most  cases  taken  place. 

Much  work  still  remains  to  be  done  on  these  lines, 
especially  in  connection  with  the  more  complex  compounds 
which  constitute  the  natural  asphalts,  such  as  gilsonite, 
grahamite,  elaterite,  and  others,  the  natural  waxes  or 
ozokerites,  as  well  as  on  the  heavy  asphaltic  crudes.  It  is 
undoubtedly  by  the  examination  of  these  bodies,  rather  than 
the  volatile  and  simpler  constituents,  that  light  will  be  thrown 
on  the  relations  of  crude  oil  with  each  other  and  with  coals, 
and  incidentally  on  the  much-discussed  question  as  to  the 
origin  of  petroleum. 

Attempts  have  been  made  to  utilize  other  physical 
characters  for  the  determination  of  the  class  to  which  a 
hydrocarbon  belongs.  Darmois  (Comptes  rendus,  1920,  p. 
952)  has  examined  the  dispersion  of  several  classes  of  hydro- 
carbons. He  finds  that  the  specific  dispersion,  i.e.  the 
difference  between  the  refractive  indices  for  two  definite 
wave  lengths,  divided  by  the  density,  is  a  constant  for 
particular  series  of  hydrocarbons.  (In  his  work  he  used  the 
two  spectrum  lines  Ha  and  Hy.) 

In  the  case  of  hexane  (n)  he  finds  density  1/4  0-6634. 


-•         ^\  ftf 

Aw =103    and   -j  = 
p. 


i8     PETROLEUM  AND  ALLIED   INDUSTRIES 
For  six  hydrocarbons  of  the  paraffin  series  and  for  nine 

/\fl7 

of  the  cycloparaffin  series  he  finds  -j-=  about  155. 

For  hydrocarbons  with  one  double  bond,  e.g.  amylene, 

/\*W 

he  finds  -^  =  about  193. 

For  hydrocarbons  with  two  double  bonds,  e.g.  methyl 

A  47. 

hexadiene,  he  finds  -^  =  about  228. 
(t 

And  for  the  aromatic  hydrocarbons  he  finds  a  value  about 
300. 

Such  work  may  prove  of  great  value  in  future 
researches. 

Apart  from  these  physical  methods,  certain  chemical 
methods  may  also  be  employed  for  the  separation  of  the 
compounds  of  crude  oil  and  for  their  estimation.  There 
are,  of  course,  objections  to  such  chemical  methods  of 
analysis,  as  the  behaviour  of  most  of  the  compounds  under 
investigation  towards  many  reagents  is  by  no  means  well 
known. 

For  example,  unsaturated  hydrocarbons  are  usually 
removed  and  estimated  by  absorption  with  sulphuric  acid, 
aromatic  hydrocarbons  by  absorption  with  oleum  in  the 
cold,  after  the  removal  of  unsaturated  hydrocarbons  (Bowrey, 
J.I.P.T.,  vol.  3,  p.  287).  These  methods  are  by  no  means 
simple,  however,  as  overlapping  of  the  action  of  the  acid 
takes  place.  Xylol,  and  higher  aromatics,  for  example,  are 
partly  removed  by  96  per  cent,  sulphuric  acid,  which  also 
causes  polymerization  of  some  of  the  unsaturated  bodies. 
Further,  oleum  certainly  reacts  with  certain  non-aromatic 
constituents  too.  The  isolation,  therefore,  of  even  any  one 
class  of  hydrocarbons,  much  more  so  of  any  individual  of  a 
class,  is  a  matter  of  difficulty.  This  is,  however,  generally 
only  a  matter  of  minor  importance  in  practice,  though  of 
greater  importance  from  the  point  of  view  of  research. 

A  further  possible  method  of  investigation  is  suggested 
by  the  recent  work  of  Tausz  and  Peter  (Zentr.  Bakt.  und 
Parasit.,  1919,  vol.  49,  p.  495  ;  and  J.5.C.7.,  vol.  39,  p.  357A) 


CHEMISTRY  19 

on  the  preferential  action  of  certain  bacteria.  They  found 
that  paraffins  can  be  separated  from  naphthenes  by  the 
action  of  B.  aliphaticum  and  B.  aliphaticum  liquefaciens, 
bacteria  which  they  isolated  from  garden  mould.  These 
species  are  inert  towards  cyclic  hydrocarbons,  but  attack 
paraffins.  In  this  manner  Tausz  and  Peter  have  isolated 
1.3  djmethylcyclohexane  and  1.3.4  trimethylcyclohexane 
from  a  petroleum.  This  method  is  as  yet  in  its  infancy, 
but  it  certainly  has  possibilities. 

Hydrocarbons  of  most  of  the  known  series  have  been 
detected  in  some  one  or  other  of  the  many  varieties  of  crude 
petroleum.  Those  of  the  paraffin  (aliphatic)  and  naphthene 
(alicylic)  series,  however,  predominate,  those  of  the  aromatic 
series  occur  to  a  less  extent  and  in  fewer  crudes,  while 
members  of  the  less  known  series  are  also  undoubtedly  of 
great  importance. 

There  is  no  known  crude  composed  exclusively  of  the 
members  of  any  one  series,  but  many  crudes  are  characterized 
by  the  presence  in  predominating  quantities  of  hydro- 
carbons of  one  of  the  series. 

The  paraffin  series  of  hydrocarbons  (CnH2n+2)  are 
widely  distributed,  occurring  to  some  extent  in  most  crudes, 
particularly  in  the  lighter  fractions.  They  enter  very  largely 
into  the  composition  of  the  crude  oils  of  the  eastern  states  of 
North  America,  to  the  almost  complete  exclusion  of  members 
of  other  series.  They  occur  to  a  less  extent  in  those  of  Galicia, 
Rumania,  Persia,  Burmah,  Mexico,  Sumatra,  etc.,  and  in 
smaller  proportions  still  in  those  of  Russia,  Borneo,  South 
America,  and  California.  The  more  volatile  members  of 
the  series,  methane  to  pentane,  occur  in  natural  gases 
and  the  higher  members  constitute  the  paraffin  waxes. 

The  liquid  members  have  lower  specific  gravities  than  do 
those  members  of  other  series  having  similar  boiling  points. 

B.p.  Sp.gr.  at  15°  C. 

Hexane  C6H14  . .         . .     70  0*662 

Cyclohexane  C6H12  . .         . .     70  0746 

Hexylene        C6H12  ..         . .     5§  °*685 

Benzene          C6H6  ..         ..80  0-884 


20     PETROLEUM  AND  ALLIED  INDUSTRIES 

Their  specific  gravities  rise  with  the  boiling  points, 
e.g.— 

w-pentane  . .  . .  sp.gr.  0*627/15°  C.  b.p.  36-3°  C. 

»-hexane   ..  ..  „     0*658/20°  C.  „     68-9°  C. 

w-heptane  . .  . .  „     0-683/20°  C.  „     98-4°  C. 

w-decane    ..  ..  „     0730/20°  C.  „  173-0°  C. 

This  is  generally  the  case,  but  the  aromatic  hydrocarbons 
show  the  reverse  effect. 

Owing  to  the  fact  that  motor  spirits  from  Appalachian 
crudes  were  early  in  the  market  low  specific  gravity  came  to 
be  regarded  as  a  criterion  of  quality,  a  popular  fallacy  which 
died  very  hard. 

In  the  case  of  a  motor  spirit  composed  entirely,  or  nearly 
so,  of  paraffin  hydrocarbons,  low  specific  gravity  is  an 
index  to  degree  of  volatility,  but  as  a  means  of  comparison 
for  motor  spirit  of  various  origins  it  is  entirely  misleading, 
as  may  easily  be  seen  from  the  fact  that  a  heavy  kerosene 
of  paraffin  hydrocarbons,  utterly  unsuitable  as  a  motor 
spirit,  has  a  specific  gravity  lower  than  that  of  benzol,  an 
excellent  motor  fuel. 

The'paraffin  hydrocarbons,  though  stable  to  most  reagents, 
readily  undergo  cracking  at  high  temperatures.  Such 
cracking  is  easily  effected  in  the  case  of  paraffin  wax  (Mabery, 
Proc.  Am.  Phil.  Soc.,  1897,  p.  135).  The  unstability  of  the 
paraffins  is  also  evident  from  the  fact  that  they  are  the 
hydrocarbons  which  most  readily  show  the  phenomena  of 
detonation  (knocking  or  pinking)  when  used  in  automobile 
internal  combustion  engines.  In  this  respect  they  show  up 
badly  in  comparison  with  the  naphthenes  and  worse  still 
in  comparison  with  the  aromatics  (Ricardo,  "  The  Influence 
of  various  Fuels  on  the  performance  of  Internal  Combustion 
Engines,"  Automobile  Engineer,  February,  1921). 

The  higher  paraffins  occur  as  waxes  also  in  wood  tar,  and 
in  the  various  oils  resulting  from  the  distillation  of  cannel 
coals  and  shales,  and  in  the  oil  produced  by  the  low  tem- 
perature distillation  of  coal.  They  occur  also  in  ozokerit,  a 
natural  wax  often  found  associated  with  petroleum,  which 


CHEMISTRY  21 

contains  the  higher  members  of  the  series  from  C24H50 
upwards. 

It  is  not  proposed  to  give  here  a  detailed  list  of  the  various 
hydrocarbons  and  their  properties.  For  these,  reference 
should  be  made  to  Engler-Hofer,  "  Das  Erdol,"  vol.  i,  where 
tabulated  analyses  of  numerous  crude  oils  are  also  given. 

The  hydrocarbons  of  the  olefine  series  (CnH2n)  are 
unsaturated  open  chain  compounds.  They  are  isomeric 
with  the  members  of  the  naphthene  series  (CnH2n-6H6) 
which,  on  the  contrary,  are  saturated  ring  compounds. 

The  defines  occur  in  crude  petroleums  comparatively 
rarely  and  in  small  quantities.  They  are,  however,  present 
in  shale  oils  and  tars  and  in  many  petroleum  distillates, 
as  they  are  among  the  products  resulting  from  the  cracking 
of  paraffins  and  other  hydrocarbons.  They  are  readily 
absorbed  by  sulphuric  acid,  are  oxidized  by  permanganate, 
and  form  addition  compounds  with  bromine.  They  are  also 
soluble  in  liquid  sulphur  dioxide,  and  may  thus  be  separated 
from  aliphatic  hydrocarbons.  This  reaction  finds  technical 
application  in  the  Edeleanu  process  (vide  Pt.  VII. ,  Sec.  C). 
They  react  with  ozone  to  form  ozonides.  The  paraffins  and 
naphthenes  do  not  react  in  this  way  (Harries,  Lieb.  Annal., 
1906,  p.  343  ;  1910,  p.  374).  They  react  with  mercury  salts, 
and  these  reactions  have  been  proposed  as  the  basis  for 
methods  of  estimation  of  these  hydrocarbons  (Engler- 
Hofer,  "Das  Erdol,"  vol.  i,  p.  269).  Small  quantities  of 
olefines  have  been  found  in  Galician,  Rumanian,  Caucasian, 
Canadian,  and  South  American  oils. 

The  members  of  the  diolefine,  acetylene,  and  other 
unsaturated  series  (Tausz,  Zeit.  angew.  Chemie,  1919,  vol.  32, 
p.  233)  are  of  minor  importance  in  petroleums,  but  are 
normal  constituents  of  many  tars  and  shale  oils.  The 
diolefines,  owing  to  their  readiness  to  undergo  oxidation  and 
polymerization,  are  undesirable  constituents  in  petroleum 
products  (other  than  liquid  fuels)  ;  in  a  motor  spirit,  for  ex- 
ample, they  give  rise  to  the  formation  of  gummy  deposits.  In 
removing  them,  unfortunately,  quantities  of  olefines,  which  in 
themselves  are  not  undesirable  constituents,  are  removed  too. 


22     PETROLEUM  AND  ALLIED  INDUSTRIES 

The  members  of  the  naphthene  or  alicylic  series,  on  the 
contrary,  play  a  very  important  part  in  the  composition 
of  well-known  crude  oils.  These  differ  from  the  olefines, 
which  have  the  same  empirical  composition,  in  that  they  are 
saturated  ring  compounds.  As  regards  their  behaviour 
towards  reagents  such  as  sulphuric  and  nitric  acids,  halogens, 
etc.,  they  stand  between  the  paraffin  and  the  aromatic 
hydrocarbons.  They  are  not  attacked  by  sulphuric  acid  in 
the  cold.  They  can  be  oxidized  by  vigorous  oxidizing 
agents,  the  ring  being  then  broken  up.  As  the  individual 
members  of  the  series,  however,  do  not  all  behave  in  the 
same  manner  towards  any  reagent,  there  is  no  general  method 
by  which  members  of  this  series  can  be  separated  from 
mixtures  with  paraffin  hydrocarbons. 

The  hydrocarbons  of  this  series  are  of  higher  specific 
gravity  than  the  corresponding  paraffins,  e.g. — 

Cyclohexane °799  at  o°  C. 

Hexane  . .         . .         . .         . .  0*676  at  o°  C. 

Methylcyclohexane      . .          . .  0778  at  o°  C. 

Heptane  . .         . .         . .  0701  at  o°  C. 

Naphthenes  occur  in  Caucasian  petroleums,  of  which  they 
constitute  a  large  proportion ;  to  a  considerable  extent  also 
in  the  petroleums  of  Galicia,  Rumania,  Egypt,  Borneo,  Peru, 
California,  and  elsewhere. 

From  the  practical  standpoint  naphthenic  crudes  yield 
good  motor  spirits,  the  naphthenes  being  superior  to  the 
paraffins  in  this  respect,  as  they  can  be  used  in  engines  of 
higher  compression  and  therefore  of  greater  thermal  effi- 
ciency. They  yield  also  kerosenes  of  good  illuminating 
quality,  and  good  lubricating  oils  of  low  cold  test. 

Hydrocarbons  of  the  aromatic  series  are  of  common 
occurrence  in.crude  petroleum,  though  generally  to  the  extent 
of  below  10  per  cent.  In  a  few  exceptional  types,  however, 
the  percentage  may  be  much  higher.  The  crude  oils  of 
East  Borneo  are  remarkable  in  this  respect,  containing  as 
much  as  40  per  cent,  of  aromatics  (Jones  and  Wooton, 
J.C.S.,  91,  pp.  114,  1146). 


CHEMISTRY  23 

These  hydrocarbons  occur  also  in  coal  tars,  especially 
in  those  resulting  from  high-temperature  distillations.  lyow- 
temperature  distillation  tars  and  shale  oils  are  relatively 
poorer  in  aromatics  and  richer  in  paraffins.  The  hydro- 
carbons of  this  series  are  of  relatively  high  specific  gravity, 
which  in  this  case  decreases  somewhat  with  the  increase  of 
molecular  weight,  e.g. — 

Benzene  0-884  at  I5°  C. 

Toluene  0*870       „ 

P.  xylene  . .         . .         . .  0*866      „ 

Cymene  0-863 

They  possess  greater  solvent  properties  than  do  the  members 
of  the  paraffin  and  naphthene  series,  so  that  good  extraction 
spirits  can  be  made  from  crudes  relatively  rich  in  these 
compounds.  They  are  readily  sulphonated  by  sulphuric 
acid  and  on  these  properties  methods  of  estimation  have 
been  based.  They  are  soluble  in  cold  liquid  sulphur  dioxide 
and  are  often  extracted  from  kerosenes  by  a  method  based 
on  this  behaviour  (vide  "Edeleanu  Process/'  Pt.  VII., 
Sec.  C).  They  are  readily  nitrated  by  a  mixture  of  sulphuric 
and  nitric  acids. 

Ross  and  feather  (Analyst,  vol.  31,  p.  285)  in  this  way 
isolated  decahydro-  and  tetrahydro-naphthalenes  from  a 
Borneo  gas-oil  distillate. 

Several  of  the  nitro-compounds,  e.g.  dinitrobenzene, 
trinitrotoluene,  trinitroxylene,  are  used  as  explosives.  The 
lower  members  of  the  series  may  be  separated  from  admixture 
with  other  hydrocarbons  by  taking  advantage  of  their  ready 
nitration,  as  the  mononitro  compounds  may  easily  be 
separated  by  distillation,  and  subsequently  converted  into 
the  trinitro  derivatives. 

Aromatic  hydrocarbons  of  the  higher  series  CnH2n-8» 
CnH2n-io>  and  so  on  have  been  found  in  small  quantities 
in  various  petroleums  and  have  been  isolated  from  the 
distillates  boiling  at  temperatures  over  200°  C.  But  as 
chemical  changes  begin  to  take  place  at  these  temperatures, 
it  is  by  no  means  proved  that  these  hydrocarbons  exist  as 


24      PETROLEUM  AND  ALLIED  INDUSTRIES 

such  in  crude  oils.  They  are  found  also  in  coal-tar  distillates. 
Indene,  for  example,  was  isolated  from  coal-tar  light  oils  by 
Kraemer  and  Spilker  (Zeit.  angew.  Chem.,  1890,  p.  734). 
Naphthalene  is  an  important  constituent  of  coal-tar  distillates, 
as  are  also  methyl-  and  phenyl-naphthalenes,  acenaphthene 
and  its  derivatives,  diphenyl,  fluorene,  anthracene,  phenan- 
threne  and  their  derivatives,  fluoranthene,  pyrene,  chrysene, 
retene,  and  others  (Malatesta,  "  Coal  Tars  and  their 
Derivatives,"  Chap.  III.),  but  many  of  these  have  also  been 
found  in  petroleums  (Engler-Hofer,  "  Das  Erdol,"  vol.  i). 

In  addition  to  the  members  of  these  main  hydrocarbon 
series,  members  of  many  other  less  known  and  little  investi- 
gated series  have  been  found.  The  presence  of  many 
saturated  hydrocarbons  of  unknown  constitution,  hydro- 
carbons of  the  terpene  series  and  of  other  more  complicated 
series  from  CwH2w_io  to  CwH2w_20  nave  been  indicated 
by  many  workers,  such  as  Mabery,  Coates,  Markownikoff, 
Engler,  Marcusson,  and  many  others.  Detailed  references 
to  these  are  given  in  Kngler-Hofer,  "  Das  Erdol,"  vol.  i. 
Hydrocarbons  of  the  series  CnH2n,  CnH2n_2  and  CnH2n_4 
have  recently  been  isolated  from  the  petroleum  extracted  from 
the  bituminous  sands  of  Alberta  (Krieble  and  Seyer,  /.  Am. 
Chem.  Soc.,  1921,  p.  1337).  Our  knowledge  of  the  properties 
of  the  hydrocarbons  of  these  series  is,  however,  very  vague  ; 
indeed  the  field  may  be  said  to  be  practically  unexplored. 

Apart  from  the  hydrocarbons  and  the  higher,  practically 
uninvestigated,  asphaltic  bodies,  many  other  compounds 
occur  as  unimportant  constituents  (usually  regarded  as 
impurities)  in  petroleums  and  as  normal  constituents  in 
tar.  Sulphur  compounds,  and  to  a  much  less  extent  nitrogen 
and  oxygen  compounds,  occur  even  in  the  lighter  fractions 
of  certain  petroleums,  more  so  in  shale  oils  and  tars  ;  of  the 
composition  of  the  higher  sulphur  and  oxygen  compounds, 
which  undoubtedly  play  an  important  part  in  the  composition 
of  many  asphalts,  very  little  is  as  yet  known.  Research  in 
this  difficult  field  should  yield  interesting  results. 

Sulphur  is  found  to  some  extent  in  practically  all  crude 
oils.  In  some  cases  it  is  an  essential  constituent  of  the  crude, 


CHEMISTRY  25 

e.g.  in  the  case  of  the  thioasphaltic  oils  of  Mexico,  in  other 
cases  it  is  merely  an  impurity  ;  in  some  cases  it  is  found  in 
solution  (Peckham,  Proc.  Am.  Phil.  Soc.,  1897,  p.  108)  in 
the  oil.  Many  crude  oils  of  Ohio,  Canada,  Mexico,  Persia, 
Egypt,  California,  and  Texas  and  elsewhere  are  relatively 
rich  in  sulphur  compounds. 

Thiophene  has  been  found  in  German  crudes,  thiophene 
and  its  homologues  in  Canadian,  Caucasian,  and  Persian  oils ; 
thioethers  in  Ohio  oils  and  mercaptans  in  Persian  oils.  The 
sulphur  compounds  occurring  in  petroleum  have,  however, 
as  yet  received  comparatively  little  attention  (Mollwo 
Perkin,  J.I.P.T.,  vol.  3,  p.  227). 

The  presence  of  sulphur  in  relatively  large  quantities 
is  interesting  to  the  student  of  the  origin  of  petroleum,  as 
such  large  amounts  as  are  sometimes  found  could  not  have 
originated  from  animal  or  terrestrial  vegetable  matter.  In 
certain  cases  sulphur  in  combination  must  have  resulted  from 
secondary  changes  owing  to  contact  of  the  oil  during  migra- 
tion with  either  sulphur  or  sulphates,  and  such  sulphates,  e.g. 
gypsum,  are  indeed  often  found  in  close  association  with 
oils  relatively  rich  in  sulphur  (Hackford/./.PT.,  1922,  vol.  8). 
Sulphur  compounds  are  usually  present  in  considerable 
quantities  in  shale  oils.  The  difficulty  of  eliminating  the 
sulphur  compounds  has  always  been  one  of  the  obstacles 
to  the  working  up  of  the  English  shales  for  oil. 

Nitrogen  compounds  occur  in  small  quantities  in  many 
crude  petroleums,  e.g.  in  Californian,  Japanese,  and  Algerian. 
They  occur  usually  in  the  form  of  homologues  of  pyridin 
(some  Californian  crudes  are  unusually  rich  in  quinolines). 
The  presence  of  nitrogen  compounds  is,  however,  of  no 
practical  importance  as  they  are  usually  eliminated  in 
refining.  They  occur  to  a  much  larger  extent  in  shale  oils 
and  various  tars,  mainly  in  the  form  of  pyridin  and  anilin 
homologues. 

Oxygen  compounds  are  found  to  some  extent  in  most 
crudes,  and  in  the  case  of  certain  asphaltic  oils  are  un- 
doubtedly an  essential  constituent.  In  certain  oils,  e.g.  some 
of  California,  the  oxygen  compounds  are  phenols  and  in  others, 


26     PETROLEUM  AND  ALLIED  INDUSTRIES 

e.g.  Russian,  naphthenic  acids.  Practically  no  work  has 
as  yet  been  done  on  the  oxygenated  compounds  present  in 
petroleums.  Phenol  and  its  homologues  form  important 
constituents  of  coal  tar,  while  other  oxygenated  products, 
e.g.  ketones  and  acids  are  found  in  wood  tars. 

Although  the  complete  examination  and  identification 
of  the  constituents  of  a  petroleum  distillate  is  too  difficult 
an  undertaking  ever  to  be  of  much  practical  value,  still  a 
ready  means  of  determining  even  approximately  the  per- 
centages of  paraffins,  naphthenes  and  aromatics  in  a  light 
petroleum  product,  for  use  as  a  motor  spirit,  is  of  prime 
importance,  owing  to  the  very  great  difference  in  value,  as 
motor  fuels,  of  the  hydrocarbons  of  these  three  groups. 
Chavanne  and  Simon  (Comptes  rendus,  1919,  p.  285)  have 
done  much  work  in  this  direction  by  applying  the  aniline 
solubility  critical  temperature  method.  Tizard  and  Marshall 
(J.S.C.I.,  40,  p.  20T)  have  developed  and  modified  this 
method  and  find  it  particularly  applicable  to  the  estimation 
of  aromatic  hydrocarbons. 

The  temperature  at  which  a  mixture  of  equal  volumes 
of  pure  freshly  distilled  aniline  and  the  benzine  separate  out 
is  called  the  aniline  point.  The  aniline  point  for  paraffins 
is  high,  about  70°  C.,  for  naphthenes  it  is  lower,  about  50°  C., 
and  for  aromatics  is  much  lower  still. 

It  has  been  found  that  the  difference  in  aniline  point 
for  a  benzine,  before  and  after  the  removal  of  the  aromatics 
by  sulphonation,  is  proportional  to  the  original  aromatic 
content,  provided  that  unsaturated  hydrocarbons  are  absent. 
Thus  a  lowering  of  aniline  point  of  4-2°  C.  corresponds  to 
5  per  cent,  by  weight  of  aromatic  hydrocarbons,  of  i8'i°  C. 
to  20  per  cent.,  of  39*8°  C.  to  40  per  cent.,  and  so  on.  The 
method  has  so  far  only  been  worked  out  for  the  first  three 
members  of  the  aromatic  series.  The  method  is  capable  of 
further  development  and  its  use  may  be  considerably 
extended. 

The  chemistry  of  coal  is  a  subject  which  has  lately 
been  receiving  much  attention,  but  is  as  yet  little  understood. 
The  subject,  however,  lies  outside  the  scope  of  this  volume. 


CHEMISTRY  27 

The  question  of  the  origin  of  petroleum  and  its  possible, 
or  probable,  relation  to  coal  has  also  been  the  subject  of 
much  discussion.  Hackford  (Trans.  Am.  Inst.  of  Mining 
and  Metallurgical  Engineers,  September,  1920)  has  converted 
petroleum  oils  by  slow  oxidation  or  thionization  aided  by 
gentle  heat  into  bodies  termed  by  him  "  kerotenes,"  most  of 
which  are  quite  insoluble  in  any  of  the  known  solvents  and 
are  probably  identical  with  certain  constituents  of  coal. 
He  has  also  shown  that  the  portions  of  coal  soluble  in  pyridine 
consisted  partly  of  asphaltenes  (i.e.  those  portions  of  bitumens 
which  are  insoluble  in  ether  or  ether-alcohol,  but  are  soluble 
in  carbon  bisulphide).  He  concludes  that  most  of  the 
insoluble  portion  of  coal  consists  of  a  true  bitumen  which 
has  been  transformed  into  an  insoluble  kerotene.  The 
kerotenes  (the  portions  of  a  bitumen  which  are  insoluble  in 
carbon  disulphide)  experimentally  produced  from  petroleum, 
yield,  on  distillation,  the  same  products  as  are  obtained  by 
the  distillation  under  the  same  conditions  of  the  kerotenes 
derived  from  coal. 

Fischer  and  Gluud  (Ber.t  1919,  p.  1053)  claim  to  have 
established  that  light  paraffins  exist  as  such  in  certain  coals. 

Tausz  (Zeit.  angew.  Chem.,  1919,  p.  361)  has  pointed  out 
that  all  three  xylenes  and  ethylbenzene  are  found,  not  only 
in  the  distillates  from  coal,  but  in  some  petroleums  too. 

A  high  melting-point  paraffin  wax  was  actually  found  in 
a  ^Lancashire  coal-seam  many  years  ago  (Sinnatt,  Colliery 
Guardian,  November  14,  1919). 

Although  the  products  up  to  the  present  commercially 
extracted  from  petroleum  have  been  in  the  main  those 
obtained  by  the  physical  methods  of  distillation  and  nitra- 
tion, i.e.  various  motor  and  extraction  spirits,  illuminating 
oils,  lubricants  of  various  grades,  fuel  oils,  waxes,  and 
asphalts,  there  are  indications  that  in  the  future  products 
obtained  by  chemical  means  will  play  an  important  part. 

Recently  alcohol  has  been  prepared  from  the  ethylene 
present  in  coke-oven  gases  by  Bury  and  Ollander  (Chem. 
Age,  1920,  p.  238,  and  Eng.  Patent  147360  of  July  22,  1920). 
The  ethylene  is  absorbed  by  concentrated  sulphuric  acid 


28     PETROLEUM  AND  ALLIED  INDUSTRIES 

and  the  ethylhydrogen  sulphate  so  formed  is  subsequently 
hydrolysed  by  steam  distillation,  yielding  ethyl  alcohol 
and  sulphuric  acid  again  in  the  well-known  manner. 

C2H4+H2S04=C2H5H.S04 
C2H6H.S04  -f  H20 =C2H5OH +H2SO4. 

In  a  similar  way  the  propylene  evolved  from  the  cracking 
stills  used  to  crack  gas  oils  into  motor  spirits  (vide  P.  VII., 
Sec.  F)  is  converted  into  isopropyl  alcohol  (Carleton-Ellis, 
Petroleum  Mag.,  January,  1921,  p.  40),  and  this  alcohol  is 
used  in  admixture  with  benzene  as  a  motor  fuel. 

By  chlorination,  chlor  derivatives  of  hydrocarbons  suitable 
for  use  as  non-inflammable  solvents  may  be  obtained.  By 
chlorination  and  subsequent  removal  of  the  chlorine,  drying 
oils  may  be  obtained. 

Much  work  has  recently  been  done  on  the  oxidation  of 
the  higher  paraffins  to  fatty  acids.  Griin,  Ulbrich,  and 
Wirth  (Ber.t  1920,  p.  987)  found  they  were  able  to  oxidize 
paraffin  wax  and  obtain  a  whole  range  of  fatty  acids  there- 
from. lySffl  (Chem.  Ztg.,  1920,  p.  561)  oxidized  petroleum 
hydrocarbons  with  the  assistance  of  lead  or  mercuric  catalysts, 
to  fatty  acids  which  when  mixed  with  tallow  or  coconut 
fatty  acids  yielded  satisfactory  acids  for  soap  making. 
Schaarschmidt  and  Thiele  (Ber.,  1920,  p.  2128)  chlorinated 
paraffin  wax,  and  after  removal  of  the  chlorine  by  alcoholic 
potassium  hydroxide  oxidized  the  hydrocarbons  to  fatty 
acids.  Fischer  and  Schneider  (Ber.,  1920,  p.  922)  oxidized 
paraffin  wax  by  means  of  air  under  pressure  to  fatty  acids. 
These  researches  foreshadow  a  possible  alternative  supply  of 
fatty  acids  for  soap  making  and  the  consequent  liberation 
of  certain  vegetable  oils  for  more  useful  purposes. 

Pentane  can  be  converted  by  a  rather  complicated  process 
into  isoprene,  the  possibility  of  synthetic  rubber  from 
petroleum  being  thus  opened  up. 

The  investigation  of  possible  petroleum  by-products  is 
one  of  the  most  promising  fields  for  research.  Our  ignorance 
of  the  chemistry  of  petroleum  as  well  as  that  of  shale  oils 
and  tars  of  various  kinds  is  really  relatively  profound. 


CHEMISTRY  29 

With  adequate  research  these  industries  will  undoubtedly 
expand  and  considerably  extend  their  yield  of  important 
products. 

A  distinctly  new  line  in  petroleum  chemistry  has  been 
struck  by  Hackford,  the  preliminary  outline  of  which  has 
been  published  by  him  in  a  paper  read  before  the  Institution 
of  Petroleum  Technologists  (J.I.P.T.,  1922,  vol.  8).  He 
has  endeavoured  to  take  a  very  broad  view  of  the  subject 
and  has  studied  and  correlated  data,  many  of  which  are  the 
result  of  his  own  investigations,  with  a  view  to  arriving  at 
some  general  conception  as  to  the  interrelation  of  various 
types  of  crude  oil  and  the  relation  to  crude  oils  of  the 
natural  gases,  and  natural  asphaltic  bodies  such  as  asphalt- 
ites,  elaterites,  and  the  like,  which  are  often  found  in  close 
association  with  them.  On  the  basis  of  this  work  he 
suggests  a  classification  for  bitumens,  which  has  the  merit 
of  being  based  on  their  chemical  compositions. 

As  all  crudes  contain  some  paraffins,  he  bases  his  classi- 
fication on  the  content  of  other  types  of  hydrocarbons, 
dividing  them  into  four  classes — 

(1)  aliphatic  oils 

(2)  aromatic  oils 

(3)  naphthenic  oils 

(4)  naphthelynic  oils. 

Bach  of  these  may  be  subdivided  into  two  classes,  viz.  thio- 
and  oxy-oils,  according  to  the  presence  of  oxy-  or  thio- 
hydrols  and/or  ethers.  He  classes  all  solid  bitumens  as 
"Petrolites,"  subdividing  them  into  those  soluble  in  carbon 
bisulphide  or  asphaltites,  and  those  insoluble  in  that  solvent 
or  kerites,  as  these  solid  bitumens  have  undoubtedly  been 
derived  from  the  corresponding  classes  of  oils. 

This  work  indicates  the  probability  of  being  able  to 
predict  the  type  of  oil  to  be  found  in  an  underground  reser- 
voir from  a  study  of  the  composition  of  the  natural  gas  and 
solid  bitumens,  which  may  be  found  in  association  therewith. 
Such  a  result  would  be  of  great  technical  importance,  quite 
apart  from  the  fact  that  a  very  profitable  line  of  research  is 
also  opened  up. 


30     PETROLEUM  AND  ALLIED  INDUSTRIES 

A  rather  interesting  development  during  the  last  year 
of  the  recent  war  was  that  of  the  extraction  of  helium  from 
natural  gas.  Certain  natural  gases  were  found  to  contain 
small  quantities  of  this  gas,  previously  known  merely  as  a 
chemical  curiosity.  Though  the  helium  content  never 
exceeded  i  *5  per  cent,  in  the  most  favourable  cases,  and  was 
usually  much  lower,  if  present  at  all,  plant  was  actually 
set  up  for  extracting  this  on  the  large  scale,  and  at  the  date 
of  signing  the  armistice,  many  thousands  of  cubic  feet  had 
been  prepared. 


GENERAL   REFERENCES   TO   PART   I.,   SECTION  C. 

Engler-Hofer,  "  Das  Erdol,"  vol.  i.     Hirzel,  Leipzig. 
Lunge,  "  Coal  Tar."     Gurney  and  Jackson. 
Malatesta,  "  Coal  Tar."     Spon.     1920. 

Tinkler  and  Challenger,  "  Chemistry  of  Petroleum."     Crosby  Lockwood 
and  Son, 


SECTION  D.— GEOLOGY 

THE  geology  of  shales  and  coal  is  comparatively  simple 
and  well  known ;  that  of  petroleum,  on  the  contrary,  is 
difficult  and  presents  many  unsolved  problems,  not  only  in 
specific  cases,  but  in  general.  The  origin  of  coals  is  invariably, 
and  of  shales  usually,  attributed  to  accumulations  of  vege- 
table matter  or  of  vegetable  matter  and  mud.  Exactly  what 
changes  took  place  accompanying  the  transition  to  coal  or 
shale  is  not  yet  understood.  Coal  and  shale  wherever  found 
occupy  the  same  relative  positions  to  the  under-  and  over- 
lying strata  as  they  have  always  done  since  their  deposition 
They  are,  in  fact,  ordinary  sedimentary  rocks,  they  have 
undergone  the  same  tectonic  changes  as  the  adjacent  strata 
and  the  applications  of  geology  to  ordinary  strata  hold 
equally  well  in  their  case.  It  is  assumed,  therefore,  that  the 
reader  is  acquainted  with  the  principles  of  geology  and  that 
nothing  more  need  here  be  said  about  the  method  of 
occurrence  of  coals  and  shales. 

As  petroleum,  however,  is  a  liquid,  the  factors  which 
determine  its  accumulation  are-  much  more  complicated. 
Petroleum  is  comparatively  seldom  found  in  its  mother 
rock,  the  strata  in  which  it  was  formed ;  migration  has 
usually  taken  place,  so  that  the  petroleum  has  either  been 
arrested  and  retained  when  suitable  conditions  existed,  or 
has  escaped  to  the  surface  and  been  lost.  This  latter  must 
have  been  the  case  in  innumerable  instances.  The  question 
of  the  ultimate  origin  of  petroleum,  therefore,  may  be 
neglected  in  studying  the  conditions  of  its  accumulation. 
Petroleum  in  some  form  or  another  is  found  in  all  the 
geological  systems  down  to  the  Cambrian.  About  50  per 
cent.,  however,  of  the  present  production  comes  from 

31 


32      PETROLEUM  AND  ALLIED  INDUSTRIES 

Tertiary  rocks,  40  per  cent,  from  Carboniferous  and  Devonian, 
and  8  per  cent,  from  Ordovician. 

The  crudes  of  Ohio,  Indiana,  and  Ontario  are  found  in 
the  Ordovician  and  Silurian ;  those  of  Pennsylvania  in  the 
Devonian.  Those  of  the  Illinois  and  Mid-continent  fields 
occur  in  the  Carboniferous,  as  does  also  the  oil  from  the 
Hardstoft  well,  recently  brought  in,  in  England.  The  oil 
shales  of  Scotland  also  belong  to  this  period.  Certain  of  the 
Wyoming  oils  belong  to  the  Triassic,  others  to  the  Jurassic 
period.  The  Kimmeridge  and  Norfolk  shales  of  England 
belong  also  to  this  system.  Much  of  the  crude  of  California, 
Mexico,  and  Texas  comes  from  the  Cretaceous.  The  crudes 
of  the  East  Indies  are  of  Tertiary  age,  as  are  also  those  of 
Galicia,  Russia,  Burmah,  and  Egypt. 

Bitumen  in  one  form  or  another  sometimes  appears  at 
the  surface  in  the  form  of  (i)  springs  of  natural  gas,  (2)  lakes 
or  flows  of  asphalt,  (3)  seepages  of  crude  oil,  and  (4)  outcrops 
of  impregnated  rocks. 

Examples  of  (i)  are  afforded  by  the  natural  gas  springs 
of  the  Baku  district,  the  gas  from  which  has  burned  for 
centuries.  (2)  The  largest  and  most  valuable  forms  of 
semi-liquid  asphalt  occur  in  South  America  as  the  famous 
asphalt  (wrongly  called  pitch)  lakes  of  Trinidad  and  Ber- 
mudez.  The  native  asphaltites,  gilsonite  and  grahamite,  are 
found  in  veins  outcropping  at  the  surface.  (3)  Crude  oil 
seepages  are  common,  and  may  be  due  to  the  oil-containing 
rock  actually  outcropping  at  the  surface  or  to  the  existence 
of  a  fissure  or  fault  through  which  oil  can  escape  to  the 
surface.  Such  seepages  are  common  in  Mesopotamia, 
Mexico,  and  elsewhere.  The  existence  of  seepages  naturally 
depends  on  the  depths  at  which  the  main  supplies  of  oil 
occur,  and  on  the  degree  of  folding  and  Assuring  to  which  the 
rocks  have  been  subjected.  In  the  case  of  the  Appalachian 
fields  of  the  eastern  United  States,  for  example,  seepages 
have  seldom  been  found  owing  to  the  fact  that  the  oil-bearing 
beds  have  been  only  slightly  tilted,  and  not  at  all  broken 
up.  In  other  regions,  such  as  parts  of  Mexico,  seepages 
are  common,  as  the  oil  occurs  in  newer  rocks  which  have 


GEOLOGY  33 

been  tilted  and  eroded.  In  some  cases  undoubtedly  the 
oil  may  have  almost  completely  escaped  through  fissures 
formed  by  faulting.  Interesting  cases  of  seepages  are  those 
in  which  the  oil  has  been  naturally  filtered  and  decolorised. 
Certain  such  "  white  oils  "  have  been  found  in  Persia, 
Russia,  and  elsewhere.  (4)  Outcrops  of  rock  impregnated 
with  oil  or  asphalt  are  also  well  known,  good  examples 
being  afforded  by  the  so-called  "  tar  sands  "  of  Athabasca, 
which  are  now  attracting  much  attention,  and  the  asphalt- 
impregnated  limestones  of  Val  de  Travers  and  L,immer,  so 
much  used  for  street  asphalt  paving. 

By  far  the  greater  quantity  of  the  world's  output  of 
bitumen  is  that  of  the  liquid  form,  crude  petroleum,  and 
this  is  obtained  from  strata  at  various  depths  by  means  of 
borings  or  wells. 

Liquid  petroleum  is  invariably  found  in  some  more  or 
less  porous  rock,  such  as  a  limestone,  or  sandstone,  which 
acts  as  a  reservoir.  In  some  cases  it  is  found  in  the  mother 
rock,  i.e.  that  in  which  it  originated,  more  often  in  some 
rock  into  which  it  has  migrated. 

The  question  of  the  porosity  and  capacity  for  holding 
petroleum  of  various  rocks  has  been  studied  by  several 
authors.  Beeby  Thompson  gives  cases  of  sands  capable  of 
holding  20  to  30  per  cent,  of  their  volume  of  oil,  and  Hager 
reckons  an  average  figure  of  about  13*5  per  cent.  A  sand 
may  thus  contain  as  much  as  a  gallon  of  oil  to  the  cubic 
foot. 

In  all  probability  never  more  than  75  per  cent,  of  the 
oil  from  a  rock  surrounding  the  bottom  of  a  well  can  be 
recovered,  and  that  only  in  the  case  of  light  oils. 

The  storage  capacity  of  a  rock  for  gas  is,  of  course, 
enormously  greater,  as  the  gas  is  often  present  under  a 
pressure  of  500  Ibs.  to  the  square  inch  or  more.  A  rock 
which  could  contain  one  gallon  of  oil  to  the  cubic  foot 
could  contain  nearly  5  cubic  feet  of  gas  at  30  atmospheres' 
pressure  (Redwood,  "  Treatise  on  Petroleum,"  vol.  i,  1913, 

P-  H3). 

In  addition  to  a  suitable  storage  rock,  another  condition 

P.  3 


34     PETROLEUM  AND  ALLIED  INDUSTRIES 

is  necessary,  viz.  a  suitable  impervious  covering  bed.  A 
fine-grained  shale  or  clay,  especially  if  wet,  best  fulfils  the 
conditions,  as  it  is  impervious  and  not  liable  to  fracture. 
Should  such  a  covering  exist,  but  be  badly  fractured,  the 
oil  will  usually  have  escaped.  The  Utica  shale  overlying  the 
petroliferous  Trenton  limestone  affords  a  good  example  of 
such  a  cover  or  cap-rock. 

It  is  comparatively  rarely  that  petroliferous  beds  are 
found  horizontal  and  undisturbed.  In  most  cases  the  strata, 
as  the  result  of  earth  movements,  have  been  folded  into 
anticlines  or  domes,  the  folds  being  sometimes  complicated 
by  faulting.  The  folding  of  the  strata  has  a  great  influence 
on  the  accumulation  of  oil  and  gas  in  consequence  of  their 

flnh'clme 


FIG.  i. — Diagrammatic  section  through  anticlinal  and  synclinal  folds. 

fluid  nature,  and  of  their  usual  association  with  water. 
Owing  to  lateral  pressure  brought  about  by  earth  move- 
ments, the  nature  of  which  cannot  be  discussed  here,  the 
once  horizontal  strata  have  been  thrown  into  wave-like  folds 
or  anticlines  and  synclines,  the  limbs  of  the  folds  being 
highly  or  very  slightly  inclined  according  to  the  conditions 
of  the  folding.  The  result  of  the  superimposing  of  a  series 
of  folds  with  axes  more  or  less  crossing  the  axes  of  the 
original  set,  is  a  dome  and  basin  structure  similar  to  that  of 
many  of  the  English  coalfields. 

These  two  types  of  structure  are  very  common,  but 
cannot  be  said  to  be  characteristic  of  oil-bearing  territory. 
In  a  field  exhibiting  such  structure  gas  will  be  found  accumu- 
lated along  the  crests  of  the  anticlines,  oil  below  this  and 


GEOLOGY  35 

water  below  the  oil.  If  no  water  is,  however,  present,  oil 
may  be  found  in  the  synclines  too.  Such  a  distribution  of 
the  oil  affords  good  evidence  of  movement  or  migration,  the 
factors  controlling  which  are  differences  in  specific  gravity 
and  capillarity  (M.  R.  Campbell,  "  Petroleum  and  Natural 
Gas  Resources  of  Canada."  Canada  Department  of  Mines, 
1914).  The  anticlines  are,  however,  often  asymmetrical,  one 
limb  of  the  fold  being  much  steeper  than  the  other.  In 
such  cases,  the  greater  portion  of  the  petroleum  will  usually 
be  found  in  the  gentler  slopes. 

Petroleum  occurring  under  these  conditions  is  often 
found  to  be  under  great  pressure.  This  pressure  may  be 
due  to  :  (a)  artesian  water  pressure,  (b)  pressure  of  forma- 
tion, the  gradually  accumulating  gas  having  had  no  chance 
of  escaping.  Advocates  for  both  theories  are  found  and 
both  theories  may  be  correct.  The  latter  view  can,  however, 
account  for  all  cases  of  pressure,  the  former  only  for  a  few. 

This  anticline  type  of  structure  predominates  in  most  of 
the  oil-fields  of  the  world,  e.g.  those  of  the  United  States, 
East  and  Mid-continent,  those  of  Russia,  Burmah,  and  the 
Dutch  East  Indies.  Such  folds  being  associated  with  moun- 
tain chains,  it  is  noticeable  that  most  of  the  large  oil-fields 
of  the  world  are  found  on  the  flanks  of  the  main  axes  of 
mountain  formation. 

Other  types  of  structure  of  less  common  occurrence  are 
(a)  the  saline  dome,  (b)  the  igneous  intrusion.  The  saline 
dome  type  of  structure  is  found  in  the  fields  of  Louisiana . 
Texas;  and  Rumania.  These  domes  contain  cores  of  crystal- 
line salt,  which  have  even,  in  some  cases,  been  thrust  up 
through  the  overlying  clays  and  sands,  the  structure  being 
then  usually  complicated  by  faulting.  This  is  the  case  in 
certain  of  the  Rumanian  fields.  The  structure  and  method 
of  formation  of  these  saline  domes  is  by  no  means  as  yet  well 
understood. 

The  igneous  intrusion  type  of  dome  is  found  in  Mexico. 
The  intrusion  of  a  core  of  igneous  rock  evidently  caused 
elevation  of  the  strata  into  domes  which  produced  suitable 
conditions  for  accumulation  of  petroleum.  In  some  cases 


36     PETROLEUM  AND  ALLIED  INDUSTRIES 

the  intrusion  of  an  igneous  plug  has  caused  tilting  up  of  the 
strata  near  the  edges  of  the  plug,  and  petroleum  has  accumu- 
lated in  these  upturned  edges,  being  sealed  by  the  actual 
intrusive  plug. 

In  many  cases  petroleum  is  found  in  strata  nearly  hori- 
zontal or  only  slightly  inclined,  provided  that  conditions  of 
sealing,  which  prevent  a  possible  escape  of  the  oil,  exist. 
Such  conditions  of  sealing  may  occur  in  various  ways.  For 
example,  a  petroliferous  sand  may  thin  out  on  a  slope,  being 
sealed  off  by  the  coming  together  of  the  over-  and  under- 
lying clays.  Faulting  may  bring  up  a  porous  petroliferous 


FfiUt-T. 


FIG.  2. — Oil-bearing  layer  sealed  by  a  fault. 

rock  against  an  impervious  bed,  and  so  make  an  efficient 
seal  (Fig.  2).  Conditions  suitable  for  petroleum  accumula- 
tion may  be,  and  are,  brought  about  in  many  different  ways 
of  which  the  above  afford  a  few  examples  only. 

The  detailed  study  of  underground  geological  conditions 
is  of  the  greatest  importance,  not  only  for  the  exploitation 
of  new  territory,  but  also  for  the  selection  of  well  sites  in 
known  fields. 

The  discovery  of  many  oil-fields  has  been  in  the  first 
instance  due  to  so-called  "  wild  catting,"  i.e.  the  sinking  of 
wells  as  a  speculation.  In  many  cases,  however,  it  is  only 
by  the  making  of  test  wells  that  an  area  can  be  proved 
petroliferous  or  not.  The  choice  of  sites  for  such  wells 


GEOLOGY  37 

should,  naturally,  always  be  guided  by  geological  data  as 
far  as  possible.  Even  in  a  proved  field  wells  may  turn  out 
11  dry  "  owing  to  some  unexpected  geological  feature,  such 
as  a  fault. 

A  careful  correlation  of  the  evidence  afforded  by  the  logs 
of  all  wells  may  enable  the  contours  of  the  underlying  beds 
to  be  plotted  out,  and  the  underground  geology  of  the  district 
to  be  eventually  thoroughly  well  understood. 


GENERAL   REFERENCES   TO   PART   I.,   SECTION   D. 

Cunningham  Craig,  "  Oil  Finding."     Arnold. 
Emmons,  "  Geology  of  Petroleum."     McGraw-Hill,  New  York. 
Engler-Hofer,  "  Das  Erdol,"  vol.  2.     Hirzel,  Leipzig. 
Hager,  "  Practical  Oil  Geology."     McGraw-Hill,  New  York. 
Panyity,    "  Prospecting   for   Oil   and   Gas."     John   Wiley   and   Sons, 
New  York. 


SECTION  E.— THEOEIES   OF   ORIGIN 

THE  problem  of  the  origin  of  petroleum  is  one,  not  only 
of  academic  interest,  but  also  of  great  practical  importance. 
It  has  received  much  attention  during  the  last  half -century, 
has  given  rise  to  much  discussion  and  a  voluminous  literature, 
and  is  still  regarded  by  many  authorities  as  by  no  means 
solved. 

At  the  outset  it  may  be  pointed  out  that  the  problem 
is  complicated  owing  to  the  great  differences  in  character 
of  different  crude  oils,  and  to  the  fact  that  in  many  cases 
petroleums  are  found  accumulated  in  rocks  which  were 
certainly  not  their  birthplace,  but  into  which  they  have 
migrated  at  some  subsequent  period. 

Theories  as  to  the  volcanic  or  inorganic  origin  of  petroleum 
were  advanced  by  Virlet  d'Aoust  and  Rozet  as  far  back  as 
1834,  by  Daubree  in  1850,  by  Chantourcois  in  1863.  This 
view  was  also  held  by  Humboldt.  Its  chief  advocate  was 
Berthelot,  who  in  1866  suggested  that  petroleum  might  be 
produced  by  the  action  of  steam  on  metallic  carbides.  This 
theory  was  also  advocated  by  Mendelejeff  in  1877,  who 
considered  that  as  carbides  have  been  found  in  meteorites 
they  might  also  be  expected  to  occur  in  the  earth's  interior. 
There  are  no  less  than  six  meteoric  stones  which  contain, 
though  in  very  minute  quantity,  carbon  compounds  of  such 
a  character  that  their  presence  in  a  terrestrial  body  would 
be  regarded  as  an  indirect  result  of  animal  or  vegetable 
life  ("Introduction  to  the  Study  of  Meteorites."  British 
Museum) .  The  modern  production  of  carbides  by  the  electric 
furnace  has  added  interest  to  this  theory,  but  present-day 
opinion  is  on  the  whole  decidedly  against  it.  The  absence 
of  petroleum  from  the  archaic  formations  also  militates 
against  this  view. 

38 


THEORIES  OF  ORIGIN  39 

The  presence  of  nitrogen  bases  and  of  complex  organic 
compounds  which  exhibit  optical  activity  may  be  taken  as 
conclusive  evidence  that  at  least  those  petroleums  which 
contain  such  compounds  are  not  of  inorganic  origin.  Un- 
less, therefore,  further  work  or  evidence  in  support  of  this 
view  be  forthcoming,  the  inorganic  theory  must,  in  the  vast 
majority  of  cases  at  any  rate,  be  considered  untenable. 

Theories  as  to  the  organic  origin  of  petroleum  fall  into 
two  groups :  (i)  animal  origin,  (2)  vegetable  origin,  both  of 
which  have  their  ardent  supporters. 

Any  theory  worthy  of  consideration  must  fit  in  with 
facts,  must  agree  with  the  evidence  both  chemical,  geolo- 
gical, and  experimental,  and  of  the  evidence,  the  geological 
probably  carries  most  weight. 

The  theory  of  the  animal  origin  of  petroleums  rests 
largely  upon  experimental  work,  often  carried  out  under 
conditions  of  temperature  which  certainly  could  never  have 
existed.  In  many  cases,  however,  e.g.  certain  fields  in 
California,  Egypt,  Borneo,  and  elsewhere,  geological  evidence 
is  also  in  favour  of  an  animal  origin. 

Warren  and  Storer,  by  the  distillation  of  Menhaden  oil 
under  pressure,  certainly  made  kerosene  oils  and  actually 
marketed  them.  Engler  (Ber.,  vol.  21,  p.  1816 ;  vol.  22, 
p.  592)  at  a  later  date  repeated  these  experiments  and 
obtained  an  oil  distillate  of  specific  gravity  0*815.  After 
removal  of  the  unsaturated  hydrocarbons  from  this  product, 
he  obtained  from  it,  by  fractional  distillation  pentane, 
hexane,  octane,  and  nonane,  together  with  a  kerosene  and 
some  paraffin  wax. 

Sterry  Hunt,  Briart,  Orton,  and  others  considered  that 
certain  of  the  American  crude  oils  found  in  limestones 
originated  therein  from  animal  remains.  Jaccard,  from  a 
study  of  the  Jura  asphalts,  arrived  at  the  same  view. 

Objections  to  the  animal  theory  origin  have  been  raised 
by  Cunningham  Craig,  who  points  out  that  no  accumulations 
containing  organic  animal  matter  in  any  quantity  are  being 
laid  down  at  the  present  day.  He  points  out  further  that 
the  animal  contents  of  marine  organisms  are  either  devoured 


40      PETROLEUM  AND  ALLIED  INDUSTRIES 

or  decay  away  before  accumulation  is  possible.  While 
admitting  that  such  accumulations  of  animal  matter  are  not 
now  forming,  it  is,  nevertheless,  possible  and  even  probable 
that  conditions  of  rapid  accumulation  have  obtained  in  the 
past.  In  fact,  there  are  many  cases  where  the  geological 
evidence  certainly  points  to  animal  sources. 

Although  the  chemical  distillations  which  have  yielded 
petroleum-like  oils  postulate  high  temperatures  which  are 
obviously  inadmissible,  as  often  proved,  for  example,  by 
the  close  proximity  of  unaltered  coal  beds,  it  must  be  allowed 
little  is  as  yet  known  as  to  the  nature  of  the  chemical  changes 
which  may  take  place  at  such  high  pressures  as  may  easily 
have  obtained  at  considerable  depth  in  the  earth's  crust. 
The  development  of  the  study  of  high-pressure  reactions 
will,  undoubtedly,  throw  further  light  on  this  question. 
The  possible  action  of  bacteria  is  also  a  point  which  must  be 
considered.  In  many  cases,  undoubtedly,  there  are  chemical 
facts  which  cannot  be  reconciled  with  the  theory  of  an 
animal  origin.  Animal  remains  are  relatively  rich  in 
phosphorus.  The  association  of  phosphorus  containing  com- 
pounds with  petroleum  is  very  unusual. 

Although  the  geological  processes  going  on  at  the  present 
day  do  not  lend  much  support  to  the  animal  origin  view, 
and  although  the  production  of  petroleum-like  compounds 
by  distillation  of  animal  matter  really  lends  no  support  (as 
the  distillation  of  vegetable  remains  also  yields  similar 
bodies),  it  can  certainly  not  be  asserted  that  in  no  instance 
is  petroleum  of  animal  origin. 

The  theory  of  vegetable  origin  on  the  contrary  rests  on 
much  surer  evidence.  Vast  accumulations  of  vegetable 
matter  have  been  formed  and  are  now  in  process  of  forming. 
Of  the  vegetable  origin  of  coal  there  is  no  doubt.  Shales, 
coals,  and  lignites  yield  on  distillation  under  suitable  con- 
ditions petroleum-like  bodies.  The  postulation  of  the 
necessary  high-temperature  conditions  necessary  for  such 
distillation  is,  however,  inadmissible,  and  is  perhaps 
unnecessary. 

Whether  vegetable  remains  have  passed  under  certain 


THEORIES  OF  ORIGIN  41 

conditions  into  coal,  and  under  other  conditions  into 
petroleum,  or  whether  coal  is  a  transition  stage  between 
vegetable  matter  and  petroleum,  are  questions  as  yet  far 
from  settled.  Cunningham  Craig  claims  that  the  remains 
of  terrestrial  vegetation  which  under  other  conditions  would 
develop  into  coal  will,  under  certain  conditions,  result  in 
petroleum. 

The  nature  of  coal  and  its  relation  to  petroleum  are  a 
subject  which  has  received  much  attention  of  late.  Fischer 
and  Gluud  (Ber.,  1919,  p.  1053)  claim  to  have  established 
that  certain  light  petroleum  hydrocarbons  do  exist  preformed 
in  certain  coals.  Mabery  (/.  Am.  Chem.  Soc.,  1917,  p.  2015), 
from  a  consideration  of  the  properties  of  vacuum  distillates 
from  Deerfoot  coal,  is  of  the  opinion  that  this  coal  is  an 
intermediate  stage  of  decomposition  between  vegetable 
remains  and  petroleum. 

Hackford  (Trans.  Am.  Inst.  of  Min.  and  Met.  Engineers, 
Sept.,  1920),  who  has  done  much  work  on  the  constituents  of 
petroleum  of  high  molecular  weights,  holds  that  petroleum 
oils  such  as  occur  in  nature  are  clearly  not  derived  from  coal, 
but  that  petroleum  may  have  been  produced  under  certain 
conditions  from  vegetable  material  containing  no  cellulose. 

In  the  present  stage  of  our  knowledge,  therefore,  no 
definite  general  explanation  of  the  origin  of  petroleum 
can  be  given.  In  certain  cases,  however,  definite  theories, 
well  supported  by  facts,  can  be  advanced.  For  example, 
Hackford  (J.I.P.T.,  1922,  vol.  8)  makes  out  a  good  case  for 
the  derivation  of  Mexican  petroleum  from  seaweed.  The 
outstanding  features  of  Mexican  petroleum  are  : — 

(1)  High  sulphur  content. 

(2)  Asphaltic  nature. 

(3)  Minute  nitrogen  content. 

(4)  Ivow  content  of  aromatics. 

(5)  Multiplicity  of  elements  present  in  the  ash  of  the  oil. 
There  is  ample  sulphur  in  the  alga  Macrocystis  pyrifera, 
which  is  nowadays  so  abundant  in  the  Gulf  of  Mexico,  to 
supply  all  that  is  necessary.      Algae  contain  little  or  no 
nitrogen.     The  practical  absence  of   aromatics  in  the  oil 


42      PETROLEUM  AND  ALLIED  INDUSTRIES 

may  be  accounted  for  by  the  absence  of  cellulose  in  the 
algae.  The  presence  of  numerous  elements  in  the  ash  also 
bears  out  this  view.  Different  oils  have  undoubtedly  origi- 
nated in  different  ways,  but  the  majority  of  crude  oils  are 
probably  of  vegetable  origin,  the  mechanism  of  formation 
being  not  yet  understood. 

Further  investigation  and  research  are  much  needed  for 
the  complete  elucidation  of  these  interesting  and  important 
problems,  especially  in  view  of  the  fact  that  the  available 
world's  supply  of  crude  oil  is  decreasing.  Eventually  the 
future  of  the  petroleum  industry  can  only  be  assured  if  the 
processes  of  nature  can  be  imitated  or  improved  upon  so  that 
vegetation,  the  pre-eminent  agent  for  utilizing  solar  energy, 
can  be  converted  into  petroleum,  so  convenient  a  source  of 
power,  and  so  valuable  as  the  source  of  innumerable  indis- 
pensable products. 

GENERAL   REFERENCES  TO   PART   I.,   SECTION   E. 

Beeby  Thompson,   "  The  Oil-fields  of  Russia."      Crosby  Lockwood 
and  Sons. 

Cunningham  Craig,  "  Oil  Finding."     Arnold. 

Dalton,  "  Economic  Geology,"  IV.     No.  7. 

Devaux,  "  Des  origines  du  petroles."     L'age  de  Fer.     May  10,  1920. 

Gentil,  "  Origine  des  petroles."     Chimie  et  Industrie.     December,  1920. 

Mabery,  /.  Am.  Chem.  Soc.,  41,  p.  1690. 

Pascoe,  "  Memoirs,  Geological  Survey  of  India,"  vol.  40,  Part  I. 

Sadtler,  Peckham,  Day,  Phillips,  Proc.  Am.  Phil.  Soc.,  vol.  35,  p.  93. 


PART  II.— NATURAL   GAS 

SECTION  A.— OCCURRENCE,    DISTRIBUTION, 
AND    COMPOSITION 

THE  term  "  natural  gas  "  as  generally  used  does  not  apply 
to  those  effusions  of  nitrogen,  carbon  dioxide,  sulphur 
dioxide,  etc.,  which  are  so  common  in  almost  every  country, 
and  which  are  often  associated  with  volcanic  action ;  nor  does 
it  include  gases  often  given  off  during  the  working  of  coal 
seams.  It  is  applied  in  this  work  only  to  those  effusions 
which  are  connected  indirectly  or  directly  with  underground 
supplies  of  petroleum. 

It  is  often  found  escaping  at  the  surface,  as  in  the  historic 
case  of  the  Caspian  Sea  area,  where  the  "  sacred  fire  "  was 
for  long  an  object  of  religious  reverence.1  It  is  the  cause 
of  the  curious  "  mud  volcanoes  "  of  Burmah  and  elsewhere, 
which  usually  afford  good  evidence  of  the  existence  of 
petroleum  in  the  vicinity.  The  output  obtained  from  such 
natural  springs  is,  however,  comparatively  insignificant. 
From  wells,  on  the  contrary,  bored  either  with  the  express 
purpose  of  yielding  gas  or  for  liquid  petroleum,  the  output 
often  attains  stupendous  figures. 

It  is  much  to  be  regretted  that  in  the  past  countless 
millions  of  cubic  feet  of  this  valuable  fuel  have  been  allowed 
to  run  to  waste,  owing  to  the  indifference  of  oil  producers 
and  the  lack  of  government  regulations  to  ensure  its  conserva- 
tion. The  history  of  the  industry  is  in  fact  an  appalling 
record  of  incredible  waste. 

It  is  estimated  that  in  the  few  years  prior  to  1912  not 

1  In  this  area  it  has  long  been  used  by  the  Tartars  for  burning  lime. 
Piles  of  limestone  were  made  over  gas  vents  or  fissures,  and  the  gas  ignited. 
When  burning  was  complete  the  fire  was  extinguished  by  smothering  with 
sand. 

43 


44     PETROLEUM  AND  ALLIED  INDUSTRIES 

less  than  425,000,000,000  cubic  feet  of  gas  were  allowed  to 
escape  in  the  Mid-continent  fields  alone.  This  amount  is 
equivalent  in  heating  value  to  about  gj  million  tons  of  fuel 
oil.  In  1913  a  single  well  in  the  Gushing  field  yielded 
1,500,000,000  cubic  feet  of  gas  before  being  shut  in. 

Beeby  Thompson  (J.I.P.T.,  vol.  8,  p.  31)  estimates  that, 
leaving  out  of  consideration  the  fields  which  yield  only 
gas,  883,000,000,000  cubic  feet  of  gas  at  least  have  been 
dissipated  into  the  atmosphere  up  to  the  end  of  1920. 
This  is  equivalent  to  a  loss  of  19,000,000  tons  of  oil,  i.e.  an 
amount  exceeding  the  total  production  of  Rumania  for  ten 
years. 

In  many  cases,  however,  the  loss  has  been  unavoidable 
owing  to  the  unexpected  finding  of  the  gas  at  very  high 
pressures  and  the  consequent  running  wild  of  the  well. 

In  the  majority  of  cases  gas  and  liquid  petroleum  are 
closely  associated,  often  occurring  in  the  same  beds.  In 
many  cases,  however,  gas  is  found  in  very  large  quantities 
in  beds  which  yield  little  or  no  oil. 

The  North  American  continent  yields  by  far  the  greater 
proportion  of  the  world's  total  output  of  natural  gas,  and  it 
is,  therefore,  in  this  area  that  the  natural  gas  industry  finds 
its  greatest  development.  The  chief  producing  fields  are 
those  of  West  Virginia,  Pennsylvania,  and  Ohio,  which  alone 
produce  about  600,000,000,000  cubic  feet  per  annum. 
California,  Iyouisiana,  Kansas,  and  Texas,  produce  also  in 
considerable  quantities.  Considerable  quantities  of  gas 
have  also  been  produced  in  Ontario ;  also  in  Alberta,  where 
the  output  reaches  75,000,000  cubic  feet  a  day.  A  certain 
output  of  gas  is  obtained  from  most  oil-fields,  so  that  apart 
from  the  gas-fields  of  the  North  American  continent,  the 
occurrence  and  distribution  of  natural  gas  may  be  taken  as 
coincident  with  that  of  crude  oil  (vide  Part  III.). 

As  will  have  been  gathered  from  the  introductory  section, 
the  gas,  when  confined  in  an  anticlinal  or  dome  structure,  lies 
in  the  crest  of  the  fold,  the  oil  lying  on  the  flanks  beneath. 
Care  must  therefore  be  selected  in  choosing  sites  for  wells. 
These  should  be  drilled  on  the  flank  of  the  anticline  or  dome 


NATURAL   GAS  45 

into  the  oil  zone,  avoiding  that  portion  occupied  by  the  gas. 
A  well  drilled  at  A  (Fig.  3)  will  penetrate  the  gas  zone  and 
will  not  yield  oil  until  all  the  gas  has  been  withdrawn.  A 
well  drilled  at  B  will,  on  the  contrary,  yield  oil,  and  this 
well  will  flow,  the  oil  being  ejected  by  the  pressure  of  the 
gas,  which  latter  will  not  appear  in  the  well  until  much  of 
the  oil  has  been  removed. 

The  gas  is,  in  this  case,  not  only  conserved  but  is  utilized 
for  the  ejection  of  the  oil,  pumping  being  thus  unnecessary. 

The  site  of  a  well  can,  however,  not  be  so  carefully 
selected  until  the  confines  of  the  underlying  oil  pool  have 
been  well  delineated,  and  this  unfortunately  cannot  be  done 
in  the  early  history  of  a  field,  when  the  gas  is  present  in 
greatest  quantity. 

In  the  Appalachian  fields  of  the  United  States  vast 
gas-fields  exist  in  the  Palaeozoic  rocks,  the  strata  of  which 
are  very  slightly  inclined,  so  that  the  fields  cover  a  large 
area.  This  gas  is  particularly  "  dry,"  containing  small 
quantities  only  of  condensable  constituents. 

The  gas  is  often  found  under  great  pressure,  500  Ibs. 
to  the  square  inch  being  quite  usual.  Pressures  as  high  as 
1500  Ibs.  have  actually  been  recorded.  When  the  gas  zone 
is  entered  accidentally,  or  sooner  than  anticipated  and 
before  adequate  precautions  have  been  taken,  the  heavy 
boring  tools  and  cable  are  often  shot  out  of  the  well  with 
great  violence. 

Gas  wells  of  40,000,000  or  50,000,000  cubic  feet  per  day 
have  often  been  drilled,  and  in  a  few  cases  an  initial  output 
of  over  100,000,000  cubic  feet  has  been  estimated. 

Natural  gas  was  utilized  for  illuminating  purposes  in 
the  United  States  as  far  back  as  1826.  In  the  early  days  of 
the  industry  huge  gas  flares  were  used  for  illuminating  the 
fields,  and  usually  burned  day  and  night.  It  was  also  largely 
used  as  fuel  for  the  drilling  boilers,  but  practically  only  a 
small  percentage  was  so  utilized,  the  greater  quantity  being 
allowed  to  run  to  waste.  It  is  only  during  the  last  decade 
or  two  that  the  value  of  this  gas  has  been  realized,  and  efforts 
made  to  conserve  the  supplies. 


'I, 


XX 


NATURAL  GAS  47 

Quantities  of  gas  are  usually  given  off  by  flowing  wells 
when  yielding  oil,  the  gas  in  such  cases  being  often  separated 
from  the  oil  by  means  of  special  "  separators  "  or  "  gas 
traps  "  and  utilized.  Natural  gas  obtained  in  this  way  is 
usually  rich  in  condensable  components  and  is  known  as 
"  casing-head  gas/' 

Natural  gases  consist  for  the  most  part  of  methane  and 
other  hydrocarbons  of  the  paraffin  series  ethane,  propane, 
butane,  etc.  Carbon  dioxide  and  nitrogen  are  also  usual 
constituents,  but  generally  in  small  quantities.  Oxygen, 
carbon  monoxide,  and  hydrogen  are  rarely,  if  ever,  present. 
There  is,  however,  very  great  variation  in  composition. 

The  dry  gas  of  the  fields  of  Pennsylvania  contain  about 
80  to  90  per  cent,  of  methane,  about  10  per  cent,  of  ethane, 
and  2  or  3  per  cent,  of  propane.  Nitrogen  is  often  present 
to  the  extent  of  a  few  per  cents.,  but  in  certain  cases,  e.g. 
that  of  the  Dexter  well  in  Kansas,  it  constitutes  the  bulk  of 
the  gas.  In  certain  Californian  gases,  the  percentage  of 
carbon  dioxide  rises  to  about  30.  The  wet  or  rich  gases 
which  escape  from  wells  which  are  yielding  oil  naturally 
contain  greater  percentages  of  the  heavier,  more  easily 
condensable  hydrocarbons,  such  as  butane,  pentane,  and 
hexane. 

Several  of  the  natural  gases  of  Kansas,  Texas,  and  Canada 
are  remarkable  in  that  they  contain  traces  of  helium  and 
other  gases  of  that  family.  As  much  as  1*8  per  cent,  of 
helium  has  been  found  in  rare  cases,  and  indeed  this  element 
has  actually  been  prepared  on  a  large  scale  from  natural  gas 
(McLennan,  /.C.5.,  vol.  118,  p.  923). 

The  natural  gas  industry  has  been  developed  mainly 
in  the  United  States  and  Canada,  which,  together,  yield  over 
95  per  cent,  of  the  world's  output.  The  extent  of  the  gas- 
fields  in  the  U.S.  has  been  put  at  over  9000  square  miles. 
Production  figures  for  the  early  days  of  the  industry  are  not 
available,  but  between  1906  and  1918  it  is  reckoned  that  the 
quantity  produced  and  consumed  amounted  to  7^  trillion 
cubic  feet.  The  total  volume  actually  produced,  much  of 
which  is  unrecorded,  must  have  been  much  larger.  The 


48     PETROLEUM  AND  ALLIED  INDUSTRIES 

actual  production  in  1918  was  720,981,141,000  cubic  feet, 
that  in  1917  (the  highest  recorded)  was  795,110,376,000  cubic 
feet  being  produced  by  39,370  wells.  The  production  in 
1919  showed  a  further  slight  decline.  The  bulk  of  the  gas 
has  come  from  Virginia,  Pennsylvania,  Oklahoma,  Kansas, 
Ohio,  California,  and  New  York. 


SECTION  B.— APPLICATIONS 

I/ESS  than  a  score  of  years  ago  the  natural  gas  industry 
may  be  said  to  have  been  non-existent.  Its  recent  develop- 
ment is  partly  due  to  the  introduction  of  legislative  measures 
for  minimizing  waste,  partly  to  the  rapidly  growing  demand 
for  motor  spirits,  and  to  the  finding  of  new  applications. 

In  many  fields  where  gas  is  found  under  pressure,  it 
is  used  instead  of  steam  for  driving  the  drilling  and  pumping 
engines,  the  exhaust  gas  being  further  utilized  as  a  fuel  for 
steam  generation,  and  for  the  domestic  needs  of  the  camp. 
It  is,  moreover,  often  collected  and  pumped  to  adjoining 
towns  and  used  for  illuminating,  heating,  and  power  purposes. 
Many  towns  in  America  are  well  supplied  with  cheap  power 
in  this  way,  the  gas  being  often  retailed  at  prices  as  low  as  a 
few  pence  per  1000  cubic  feet. 

The  heating  values  (gross)  in  B.  Th.  Units  for  one  cubic 
foot  of  various  gases  at  o°  C.  and  760  mm.  pressure  are  : — 

Methane  . .  Sp.  gr.  0-553  •  •  •  •  I0^5 

Ethane  . .  „       1*049  •  •  •  •  I^^1 

Propane  . .  „       1*520  . .  . .  2654 

Butane  . .  „       2*004  . .  . .  3447 

Pentane  . .  . .  . .  4250 

i  cubic  metre  of  average  natural  gas  may  be  taken  as 
equivalent  to  1*5  Kgs.  coal  as  regards  heating  value. 

A  very  important  product  derived  from  natural  gas 
is  carbon-black.  This  is  an  amorphous  form  of  carbon  or 
soot  produced  by  the  incomplete  combustion  of  natural 
gas.  It  is  not  to  be  confused  with  lamp-black,  which  is  an 
inferior  material  made  by  the  combustion  of  turpentine, 
resin,  or  such  bodies.  Carbon-black  is  much  superior  to 
p.  49  4 


50     PETROLEUM  AND  ALLIED   INDUSTRIES 

lamp-black  as  a  pigment — in  fineness,  miscibility  with  oil, 
and  covering  power.  A  cubic  inch  of  carbon-black  is  esti- 
mated to  have  a  surface  of  1,905,000  square  inches,  the 
same  volume  of  lamp-black  having  only  1,524,000, 

It  is  manufactured  by  burning  natural  gas  with  a  limited 
supply  of  air  under  such  conditions  that  the  carbon,  which  is 
produced  in  the  inner  part  of  the  flame  where  the  temperature 
is  sufficiently  high  to  decompose  the  gas,  but  where  the 
oxygen  supply  is  low,  is  quickly  cooled  by  being  deposited 
on  a  cooled  surface. 

Three  types  of  plant,  using  the  disc,  plate,  and  cylinder 
processes  are  in  common  operation,  the  principle  underlying 
each  being  the  same  (Roy.  O.  Neal,  Chem.  and  Met.  Eng., 
1920,  p.  785). 

In  the  disc  or  Blood  process,  the  gas  is  burned  and  the 
flames  allowed  to  impinge  on  a  cast-iron  rotating  disc  of 
3  to  4  feet  in  diameter,  the  carbon-black  being  scraped  off 
into  a  hopper  as  formed.  In  the  plate  or  Cabot  system,  a 
large  number  of  plates  are  arranged  horizontally  in  a  circle. 
The  burners  and  scrapers  revolve  underneath  the  plates  on 
a  central  axis.  In  the  roller  system  devised  also  by  Blood, 
the  flames  impinge  on  rotating  rollers,  from  which  the 
carbon-black  is  scraped  off.  This  system  produces  a  black 
of  better  quality,  but  the  yield  is  smaller. 

All  these  processes  produce  only  about  0*8  to  1*4  Ibs.  of 
carbon-black  per  1000  cubic  feet  of  gas  burnt.  They  appear 
very  wasteful  methods,  but  are  apparently  the  only  practical 
processes  known  which  produce  the  carbon-black  most  sought 
after  by  the  printing  trade. 

The  quantity  of  carbon-black  produced  in  the  U.S.A.  in 
1920  amounted  to  51,321,892  Ibs.  For  the  manufacture  of 
this  quantity  40,600,000,000  cubic  feet  of  gas  were  consumed, 
the  average  yield  per  1000  cubic  feet  of  gas  thus  amounting 
to  1*26  Ibs. 

Thirty-nine  plants  in  all  were  in  operation.  The 
producing  States  and  their  percentage  output  were  West 
Virginia  52,  Louisiana  36,  Wyoming,  Montana,  and  Kentucky 
together  n,  and  Pennsylvania  i. 


APPLICATIONS  OF  NATURAL  GAS  51 

Carbon-black  is  used  primarily  for  the  manufacture  of 
printing  ink.  One  pound  of  carbon-black  will  suffice  to 
print  2250  copies  of  a  sixteen-page  newspaper.  About 
35  per  cent,  of  the  entire  output  is  used  for  this  purpose. 
It  is  also  largely  used  in  the  rubber  tyre  industry.  The 
addition  of  carbon-black  renders  the  rubber  more  resilient. 
It  increases  the  tensile  strength  of  the  rubber  by  about 
25  per  cent,  and  the  elasticity  by  about  10  per  cent. 

About  10  per  cent,  of  the  total  production  is  used  for 
stove  polishes,  I  per  cent,  for  gramophone  records,  and 
large  quantities  for  paper  manufacture,  Chinese  and  Indian 
inks,  marking  inks,  boot  polishes,  tarpaulins,  varnishes, 
etc.  (Perrot  and  Thiessen,  J.  Ind.  and  Eng.  Chem.,  vol.  12, 

P-  325). 

The  great  value  of  the  condensable  portions  of  natural 
gas  for  admixture  into  motor  fuels  has  given  rise  to  an  impor- 
tant industry  of  recent  years.  In  1903  motor  spirits  were 
first  collected  from  the  condensates  in  natural  gas  pipes, 
and  in  1905  the  first  plant  designed  for  the  specific  purpose 
of  recovery  of  these  valuable  volatile  spirits  from  natural 
gas  was  erected.  Since  that  date  the  development  has  been 
considerable.  In  1914,  in  the  United  States  alone  386 
plants  were  in  operation,  treating  about  17,000,000,000 
cubic  feet  of  gas  and  obtaining  therefrom  42,650,000  gallons 
of  light  motor  spirit.  In  1920  the  quantity  had  increased 
to  383,311,817  gallons,  an  amount  which  was  extracted 
from  495,883,700,000  cubic  feet  of  gas,  an  average  of  077 
gallon  per  1000  cubic  feet.  Nearly  75  per  cent,  of  this 
was  extracted  by  the  compression  process.  This  amount 
represents  nearly  8  per  cent,  of  the  total  output  of  the  United 
States  of  motor  spirits  for  that  year.  The  industry  has  been 
developed  in  other  fields  in  other  parts  of  the  world,  but 
as  it  is  primarily  an  American  industry,  the  American  term 
"  Casing-head  gasoline  "  will,  in  future,  be  used  to  desig- 
nate the  product,  this  name  having  come  into  general  use  in 
the  petroleum  industry. 

In  addition  to  the  natural  gas  obtained  from  gas  wells, 
much  casing-head  gas  also  flows  together  with  crude  oil  from 


52      PETROLEUM  AND  ALLIED  INDUSTRIES 

oil  wells,  this  gas  being  consequently  richer  in  benzine 
(gasoline).  Gases  are  usually  designated  "  dry,"  "lean," 
or  "  wet  "  according  to  their  gasoline  content. 

"  Dry "  gases  are  composed  chiefly  of  methane  and 
ethane  and  yield  no  condensable  portions;  "lean"  gases 
contain  also  proportions  of  propane,  butane,  and  pentane ; 
and  "  wet  "  gases  contain  also  proportions  of  the  vapours 
of  hexane,  heptane,  and  perhaps  some  of  the  more  volatile 
naphthene  hydrocarbons,  e.g.  hexa-methylene. 

Two  methods  of  treatment  for  the  extraction  of  casing- 
head  gasoline  are  in  general  use,  the  compression  and 
absorption  methods,  the  former  being  usually  applied  to 
rich,  the  latter  to  lean  gases. 

The  Compression  Process. — The  gas  is  pumped  from 
the  fields  and  after  passing  through  a  drip  tank  (i)  to  trap 
any  condensed  gasoline,  enters  the  low-stage  compressors  (2). 


FIG.  4. — Diagram  illustrating  operation  of  compression  gasoline  plant. 

After  compression  it  passes  through  the  cooling  coils  (4), 
and  then  goes  on  to  the  high-stage  compressors  (6).  After 
further  compression  it  passes  through  the  cooling  coils  (7). 
The  gasoline  which  separates  out  is  drawn  off  from  the 
separating  tanks  (3  and  5).  The  cooled  compressed  gas  then 


APPLICATIONS  OF  NATURAL  GAS  53 

goes  on  into  the  regenerative  expansion  coils  (n)  and  expan- 
sion motor  (9) ,  the  exhaust  from  which  passes  back  through 
the  regenerator  expansion  coils  (n).  Compressors  of  any 
well-known  type  are  used,  the  gas  being  compressed  up  to 
20  to  50  Ibs.  per  square  inch  in  the  low-pressure  stage.  The 
gas,  heated  by  compression,  is  then  cooled,  a  certain  amount 
of  condensate  being  formed  which  is  separated  off,  depending 
of  course  on  the  nature  of  the  gas  under  treatment.  The 
gas  is  then  further  compressed  in  the  second  set  of  compressors 
up  to  as  much  as  300  Ibs.  per  square  inch  or  more.  The 
gas,  now  at  a  temperature  of  perhaps  250°  C.,  owing  to  the 
compression,  is  again  cooled.  In  the  second  set  of  coils,  a 
further  quantity  of  condensate  separates  out.  The  residual 
gas  is  then  further  cooled  by  expanding  and  doing  work  in 
an  expansion  motor,  the  cold  exhaust  from  which  further 
cools  the  gas  on  its  way  to  the  motor,  so  that  a  further 
condensate  is  obtained. 

General  practice  shows  that  a  gas  of  sp.  gr.  0-9  (air=i) 
is  about  the  leanest  which  can  be  successfully  handled 
by  a  compression  plant. 

The  gasoline  obtained  is  too  volatile  (and  too  valuable)  for 
general  use,  and  is  consequently  used  for  blending  with  heavier 
grades  of  gasoline  to  make  motor  spirits.  Mixtures  contain- 
ing a  large  quantity  of  such  compressor  gasoline,  suffer  much 
evaporation  loss  on  standing,  e.g.  a  mixture  of  50  per  cent, 
compressor  gasoline  of  sp.  gr.  0*630,  and  50  per  cent,  gasoline 
of  sp.  gr.  0739  on  standing  in  an  ordinary  graduated  litre 
cylinder  for  one  hour  lost  4  per  cent,  by  evaporation. 

The  Absorption  Process. — The  first  absorption  plants 
were  installed  on  the  gas  transmission  lines  for  absorbing 
as  much  as  possible  of  the  condensable  vapours  in  order  to 
avoid  the  deterioration  of  the  rubber  jointings  and  the 
formation  of  condensed  liquid  in  the  line  pipes.  The  installa- 
tion of  such  drying  absorption  plants  is  commercially 
justifiable  on  these  grounds  alone. 

Much  natural  gas  contains  too  little  gasoline  for  extraction 
by  the  compression  system  (f  gallon  gasoline  per  1000  cubic 
feet  is  the  practical  minimum),  but  may  be  economically 


54     PETROLEUM  AND  ALLIED  INDUSTRIES 


<5fts  OUTLET 


treated  by  an  absorption 
plant,  even  if  the  gaso- 
line content  is  as  low  as  one 
pint  per  1000  cubic  feet. 

The  operation  of  an 
absorption  plant  is  similar 
to  that  of  the  benzol  wash- 
ing plants,  so  largely  used 
during  the  war,  for  the 
recovery  of  benzol  from 
coal  gas. 

The  natural  gas  is 
passed  through  a  series  of 
absorption  towers  where 
it  meets  a  descending 
stream  of  non  -  volatile 
distilled  oil,  which  dis- 
solves out  the  condensable 
portions  of  the  gas.  The 
gasoline  is  then  recovered 
from  solution  in  the  heavy 
oil  by  distillation,  the 
gasoline  -  free  heavy  oil 
being  used  over  again. 
The  factors  which  control 
the  design  of  the  plant 
are  pressure,  temperature, 
gasoline  content  of  the 
gas,  time  of  contact  with 
the  absorbing  medium 
together  with  the  nature 
of  the  tower  packings, 
and  other  such  details 
which  affect  the  efficiency. 
The  higher  the  pressure, 
the  §«***  the  absorp- 
tion,  but  too  great  an 
absorption  means  too  great  a  loss  by  evaporation  when  the 


4O/J.  OUTLET 


APPLICATIONS  OF  NATURAL  GAS  55 

gasoline  is  subsequently  distilled  and  blended.  The  lower 
the  temperature,  the  better  the  absorption.  The  intimacy 
of  contact  is  affected  by  the  nature  of  the  tower  packing, 
and  the  time  of  contact  must  be  sufficiently  long. 

The  absorbers  in  most  general  use  are  of  the  vertical 
tower  type.  I^ean  gases  are  treated  at  higher  pressures 
than  are  rich  gases,  so  the  construction  of  the  tower  must 
be  arranged  for  accordingly.  They  are  usually  constructed 
of  diameters  up  to  12  feet  and  of  height  20  to  60  feet  or 
more  (Fig.  5). 

A  grating,  on  which  the  filling  rests,  is  placed  a  few 
feet  above  the  bottom,  the  gas  being  introduced  by  a  pipe 
entering  below  the  grating.  The  absorbing  oil  is  introduced 
a  few  feet  below  the  top  of  the  tower,  being  distributed  over 
the  surface  of  the  packing  by  a  perforated  pipe.  The 
extracted  gas  outlet  and  solution  outlet  are  placed  at  the 
top  and  bottom  of  the  tower  respectively.  Several  towers 
are  usually  arranged  in  series  and  connected  by  piping 
so  that  any  one  can  be  by-passed  for  repairs  without  shutting 
down  the  plant.  The  towers  are  designed  so  that  the 
velocity  of  the  gas  is  from  30  to  75  feet  per  minute  in  the 
unpacked  portion  of  the  tower. 

The  towers  are  filled  with  wood  gratings,  cobbles  or 
other  form  of  packing.  The  modern  forms  of  packing  such 
as  Raschig  rings  or  those  of  the  types  used  in  acid  absorp- 
tion towers  would  certainly  be  more  efficient,  as  the  surface 
presented  per  cubic  foot  of  volume  is  so  much  greater. 

The  oil  used  for  absorbing  is  generally  a  heavy  distillate, 
such  as  gas  oil,  heavy  kerosene  or  light  lubricating  oil 
fractions.  The  initial  boiling  point  of  the  absorbing  oil 
should  be  much  higher  than  the  final  boiling  point  of  the 
absorbed  gasoline,  in  order  to  render  the  subsequent  separa- 
tion by  distillation  as  easy  and  effective  as  possible. 

The  absorbing  oil  should  also  be  of  low  viscosity  and  of 
a  type  which  does  not  readily  emulsify.  It  should  be  cooled 
as  far  as  possible  before  entering  the  tower.  For  this  purpose 
cooling  coils  immersed  in  water  are  usually  used.  About 
3  or  4  square  feet  of  cooling  surface  per  gallon  of  oil  per 


56     PETROLEUM  AND  ALLIED  INDUSTRIES 

minute  is  usually  allowed,  but  this  of  course  depends  on  the 
temperature  of  the  incoming  oil. 

When  the  gasoline  content  in  the  oil  rises  to  about 
4  per  cent,  the  absorbing  power  begins  to  fall  off.  The 
amount  of  oil  circulated  varies  enormously  in  practice 
according  to  conditions  and  the  character  of  the  gas,  from 
3  or  4  gallons  to  as  much  as  70  per  1000  feet  of  gas,  7  to  10 
being  the  usual  figure. 

After  leaving  the  towers  (i)  the  oil  flows  into  the 
"  weathering  tanks,"  (2)  where  it  is  allowed  to  stand  at  a 
reduced  pressure  in  order  to  give  up  some  of  the  gas  which  it 


FIG.  6. — Diagram  illustrating  operation  of  absorption  gasoline  plant. 

dissolved  in  the  tower.  This  gas  could  not  be  recovered  as 
gasoline  by  distillation  and  is  usually  not  sufficiently  rich  for 
retreating.  It  is  passed  on  into  the  extracted  gas  mains  with 
the  rest  of  the  treated  gas. 

From  the  weathering  tank  the  oil  is  passed  through  the 
heat  exchangers  (3),  to  the  still  (4),  where  the  dissolved 
gasoline  is  distilled  off  and  condensed,  the  gasoline-free 
oil  returning  via  the  heat  exchangers  and  the  cooling  coil  (5), 
to  the  top  of  the  absorption  tower  (i).  The  same  absorbing 
oil  is  thus  used  over  and  over  again,  a  small  amount  of  make- 
up oil  being  added  from  time  to  time  to  balance  unavoidable 
losses. 


APPLICATIONS  OF  NATURAL  GAS  57 

The  heat  exchangers  used  are  of  the  ordinary  types, 
for  a  description  of  which  reference  may  be  made  to 
Part  VII.,  Section  A. 

Any  of  the  ordinary  types  of  still  may  be  used,  as  the 
operation  of  separating  the  volatile  gasoline  from  the  heavy 
absorbing  oil  is  very  simple.  The  ordinary  form  of  steam 
redistillation  still  is  often  used,  the  oil  from  the  absorber 
being  admitted  into  the  column.  A  simple  vertical  still 
fitted  with  steam-heated  baffle  plates  and  supplied  with  a 
live  steam  coil  at  the  bottom  would  also  serve  quite  well. 
For  details  as  to  still  construction  reference  may  be  made  to 
the  section  on  "Distillation  of  Crude  Oil"  (see  Pt.  VII., 
Sec.  A).  Fire-heated  stills  are  however  rarely  used. 

The  gasoline  produced  from  absorption  plants  has  a 
higher  specific  gravity  and  a  lower  vapour  pressure  than 
has  compression  gasoline  owing  to  its  lower  dissolved  gas 
content.  It  naturally  also  possesses  none  of  the  heavy 
fractions  found  in  gasoline  distilled  from  crude.  About 
80  per  cent,  of  the  product  may  be  expected  to  boil  over 
below  100°  C.  in  an  Engler  flask,  and  the  final  boiling  point 
will  be  under  150°  C. 

Absorption  plants  are,  on  the  whole,  more  efficient  and 
much  cheaper  in  operation  than  those  of  the  compression 
type.  An  absorption  plant  can  indeed  be  operated  suc- 
cessfully on  the  exhaust  gases  from  a  compression  plant, 
and  several  such  plants  have  been  installed.  The  gasoline 
from  absorption  plants,  moreover,  loses  relatively  less  by 
evaporation  on  standing  than  does  compressor  gasoline. 
A  modification  of  the  absorption  plant  which  is  sometimes 
used,  consists  in  replacing  the  absorbing  oil  by  heavy 
benzine,  so  that  this  benzine  becomes  lighter  and  more 
volatile  and  is  used  for  blending,  the  distillation  process 
being  thus  avoided.  This  type  of  absorbing  plant  is  often 
used  in  connection  with  the  recovery  of  vapours  given  off 
during  the  distillation  of  crude  oil  or  distillates,  the  distilling 
loss  being  in  this  way  considerably  reduced. 

In  addition  to  the  two  processes  above  described  there  is 
a  third  which  has  so  far  not  found  extensive  application, 


58      PETROLEUM  AND  ALLIED  INDUSTRIES 

but  which  gives  good  promise  of  future  development.  It 
is  based  on  the  absorptive  power  of  charcoal  (Anderson  and 
Hinckley,  J.  Ind.  and  Eng.  Chem.,  vol.  12,  1920,  p.  735  ; 
Oberfell,  Sprinkle,  and  Meserve,  ibid.  vol.  n,  1919,  p.  197  ; 
Burrell  and  Oberfell,  Oil  and  Gas  Journal,  July,  1920,  p.  84). 
Three  vertical  absorbers  20  to  35  feet  high  and  2  to  3  feet 
diameter  are  used.  They  are  packed  with  a  special  porous, 
granulated  charcoal.  The  gas  is  passed  through  the  first 
absorber  until  the  charcoal  is  saturated,  and  is  then  passed 
into  the  second,  the  gasoline  being  distilled  out  of  the  first 
by  means  of  steam.  Each  unit  acts,  therefore,  both  as 
absorber  and  still.  The  charcoal  lasts  indefinitely  and 
indeed  its  action  improves  with  use.  A  portable  apparatus 
for  the  examination  of  natural  gases  in  the  field,  based  on 
this  action  of  charcoal,  has  been  designed. 

In  1907  Cady  and  McFarland  (/.  Am.  Chem.  Soc.,  vol. 
29,  p.  1523)  had  already  discovered  the  presence  of 
helium  in  Kansas  natural  gas,  In  1916,  a  survey  of  most 
of  the  available  natural  gases  in  the  British  Empire  was 
made,  and  it  was  found  that  certain  gases  from  Ontario 
and  Alberta,  Canada,  contained  this  gas  in  quantities  up  to 
036  per  cent.  Certain  gases  in  Texas,  however,  contain 
nearly  2  per  cent.  The  superiority  of  helium  over  hydrogen 
as  a  gas  for  filling  airship  envelopes,  and  the  urgent  need 
for  supplies  at  any  cost,  gave  rise  to  a  wonderful  helium 
industry,  which  at  the  date  of  signing  of  the  armistice  in 
1918  was  a  technical  and  almost  a  commercial  success. 
The  method  used  for  the  extraction  of  the  helium  was  that 
of  producing  refrigeration  sufficient  to  liquefy  all  the  gases 
except  the  helium,  this  method  being  applied  in  the  Norton 
plant,  similar  in  general  to  the  Claude  oxygen-making  plant 
(Mcl^ennan,  J.C.S.,  vol.  107,  p.  20,  p.  923). 

Helium  of  97  per  cent,  purity  was  obtained  at  a  cost  of 
as  low  as  2%d.  per  cubic  foot,  a  notable  achievement  indeed, 
considering  that  but  a  few  years  ago  helium  was  merely 
a  chemical  curiosity. 

It  has  been  estimated  that  the  United  States  alone  could 
produce  nearly  a  million  cubic  feet  of  helium  daily. 


APPLICATIONS  OF  NATURAL  GAS  59 


GENERAL  REFERENCES  TO  PART  II.,   SECTION  B. 

Burrell,  Biddison  and  Oberfell,  "  Extraction  of  Gasoline  from  Natural 
Gas  by  Absorption  Methods."  Bulletin  120,  U.S.  Bureau  of  Mines. 

Burrell  and  Oberfell,  "  Composition  of  Natural  Gas."  Technical  Paper 
109,  U.S.  Bureau  of  Mines. 

Burrell,  Siebert,  and  Oberfell,  "  Condensation  of  Gasoline  from  Natural 
Gas."  Bulletin  88,  U.S.  Bureau  of  Mines. 

Dykema,  "  Recovery  of  Gasoline  from  Natural  Gas  by  Compression." 
Bulletin  151,  U.S.  Bureau  of  Mines. 

Dykema,  "  Recent  Developments  in  the  Absorption  Process."  Bulletin 
176,  U.S.  Bureau  of  Mines. 

Dykema  and  Neal,  "  Absorption  as  applied  to  Recovery  of  Gasoline 
left  in  Residual  Gas  from  Compression  Plants."  Technical  Paper  232, 
U.S.  Bureau  of  Mines. 

Henderson,  "  The  Natural  Gas  Industry,"  J.I.P.T.,  vol.  2,  p.  195. 

McLennan,  "  Some  Sources  of  Helium  in  the  British  Empire."  Bulletin 
31,  Canadian  Department  of  Mines. 

Westcott,  "  Handbook  of  Casing-head  Gas."  Metric  Metal  Works, 
Erie,  Pa. 

Westcott,  "  Handbook  of  Natural  Gas."  Metric  Metal  Works,  Erie, 
Pa. 


PART  III.— CRUDE    PETROLEUM 

SECTION  A.— OCCURRENCE,   DISTRIBUTION, 
AND   CHARACTER 

BITUMEN  in  its  liquid  form  has  been  found  in  almost  every 
country  of  the  globe,  in  many  cases,  however,  only  in  small 
quantities  incapable  of  commercial  exploitation.  As  about 
65  per  cent,  of  the  earth's  land  surface  is  made  up  of  sedi- 
mentary rocks,  and  as  enormous  areas  have  not  yet  been 
examined,  the  possibilities  of  future  development  are  great, 
even  when  taking  into  consideration  the  limitations  arising 
from  the  need  of  the  existence  of  tectonic  structures  suitable 
for  petroleum  reservoirs. 

The  recent  discovery  of  oil  in  Northern  Canada  (Oil  News, 
1920,  p.  1051)  undoubtedly  foreshadows  many  such  develop- 
ments in  the  near  future* 

Although  so  widely  distributed,  the  bulk  of  the  world's 
supplies  up  to  the  present  have  been  drawn  from  a  relatively 
small  number  of  important  areas,  many  of  which  have  already 
reached  their  peak  production.  Certain  fields  of  Russia 
and  the  United  States  have  produced  steadily  for  half  a 
century ;  fields  discovered  at  later  dates,  e.g.  those  of  Mexico 
and  Persia,  are  now  important  producers ;  others,  e.g.  those  of 
South  America,  are  as  yet  in  their  infancy.  Crude  oils  from 
different  fields  show  great  variation  in  character,  as  is  only 
to  be  expected  from  the  fact  that  they  are  drawn  from  strata 
of  very  varying  geological  ages,  and  have  been  formed  in 
varying  ways,  from  varying  materials. 

In  many  cases,  therefore,  as  might  be  expected,  a  field 
yields  different  types  of  oils  from  strata  at  different  depths, 
e.g.  those  of  Alsace  and  East  Borneo,  though,  broadly  speaking, 
the  crudes  of  any  one  field  usually  belong  to  one  type,  in 

many  cases  quite  characteristic  of  the  particular  field. 

60 


CHARACTERS   OF   CRUDE  OILS  61 

The  main  producing  fields  with  the  chief  characters  of 
their  crudes  are  detailed  below. 

Although  crude  oils  vary  enormously  in  character  from 
the  remarkable  white  oils  (which  are  naturally  filtered  oils 
of  comparatively  rare  occurrence  and  of  no  economic 
importance),  and  the  very  light  oils  rich  in  volatile  fractions, 
such  as  those  of  Sumatra,  to  the  heavy  viscous  oils  found  in 
parts  of  Mexico,  they  may  be  divided  roughly  into  three 
main  groups,  (a)  the  paraffin-base  oils,  (b)  intermediate- 
or  mixed-base  oils,  and  (c)  naphthene-  or  asphalt-base 
oils.  These  last  two  groups  are  usually  included  in  the 
term  "  asphalt-base  oils/' 

Paraffin-base  crudes  are  those  containing  relatively 
high  percentages  of  aliphatic  hydrocarbons,  naphthene-base 
oils  those  containing  relatively  high  percentages  of  cyclic 
hydrocarbons. 

Distillates  of  a  given  boiling  range  from  paraffin-base  oils 
have  a  lower  specific  gravity  than  do  those  of  similar  boiling 
range  from  naphthene-base  oils.  Also  paraffin-base  dis- 
tillates are  of  lower  viscosity  than  naphthene-base  distillates 
of  the  same  boiling-point  range,  or,  expressed  in  another  way, 
naphthene-base  oils  have  lower  flash-points  than  paraffin-base 
oils  of  the  same  viscosity  (Dean,  Nat.  Pet.  News,  1921,  p.  24A). 

The  term  "  paraffin-base  crude  "  is  often  used  to  mean, 
containing  relatively  large  percentages  of  paraffin  wax. 
Numerous  inconsistencies  will  be  found  to  occur,  e.g.  the 
distillates  of  certain  types  of  Borneo  crude,  which  are 
certainly  rich  in  paraffin  wax,  are  of  very  high  specific 
gravity  owing  to  the  presence  of  relatively  large  quantities 
of  aromatic  hydrocarbons. 

The  Appalachian  field,  once  the  most  important,  is 
the  oldest  field  in  the  United  States.  It  includes  all  the 
fields  east  of  Central  Ohio,  i.e.  those  of  Pennsylvania,  New 
York,  Kentucky,  South-east  Ohio,  North  Alabama,  Tennessee, 
and  West  Virginia.  The  crudes  from  this  area  are  of  the 
paraffin-base  type,  and  are  of  Devonian  and  Carboniferous 
age.  They  contain  as  a  rule  2  to  3  per  cent,  of  paraffin 
wax.  They  are  of  light  specific  gravity,  usually  varying 


62      PETROLEUM  AND  ALLIED  INDUSTRIES 

from  0*790  to  0*825.  They  consist,  for  the  most  part,  of 
saturated  hydrocarbons  of  the  paraffin  series.  They  are 
relatively  free  from  sulphur,  rich  in  benzine,  and  yield  good 
lubricating  and  cylinder  oils. 

The  ratio  carbon/hydrogen  is  the  lowest,  viz.  6*2. 

The  crudes  of  the  Lima-Indiana  field,  comprising 
Indiana  and  North-west  Ohio,  are  of  similar  nature,  but  are 
contaminated  with  sulphur  compounds,  which  make  the 
refining  of  these  oils  more  difficult.  They  are  of  somewhat 
higher  specific  gravity  as  they  contain  hydrocarbons  other 
than  paraffins.  They  are  of  Ordovician,  Silurian,  and  Car- 
boniferous age. 

Those  of  the  Illinois  field  are  of  naphthene-base,  but 
also  contain  some  paraffin  wax.  They  contain  small  per- 
centages of  sulphur  compounds.  They  are  mostly  of 
Carboniferous  age. 

The  fields  of  Oklahoma,  Kansas,  Louisiana,  and  North 
Texas  are  usually  grouped  as  the  Mid-Continent  field. 
Several  types  of  crude  are  here  found,  both  of  asphalt- 
and  paraffin-base,  with  varying  per  cents,  of  sulphur,  and 
varying  benzine  content.  They  resemble  on  the  whole  the 
crudes  of  Texas  and  California  rather  than  those  of  the 
Appalachian  type.  They  occur  in  Tertiary,  Cretaceous,  and 
Carboniferous  strata. 

The  Gulf  field  includes  those  of  South  Texas  and 
South  Louisiana.  These  fields  yield  oils  of  several  types, 
both  light  oils  of  sp,  gr.  0*820  to  0*850,  somewhat  similar  to 
those  of  Ohio,  of  a  mixed-base  type,  and  heavy  oils  of 
sp.  gr.  0*920  to  0*970  containing  no  paraffin  wax.  They  are 
mostly  of  Cretaceous  and  Tertiary  age.  These  oils  contain 
hydrocarbons  of  the  series  CnH2w— 2  an(i  CwH2w_4,  terpenes 
and  naphthenes. 

The  carbon/hydrogen  ratio  is  about  6*9,  and  sulphur 
is  present  in  amounts  up  to  2  per  cent. 

The  Rocky  Mountain  area  includes  the  fields  of 
Colorado,  Wyoming,  Utah,  New  Mexico,  and  Montana. 
These  crudes  are  of  naphthene-base  type  and  of  Carboniferous 
and  Cretaceous  age. 


OCCURRENCE  OF  CRUDE  OIL  63 

California  is  now  the  chief  producing  state.  The  oils 
from  its  many  fields  differ  very  considerably.  Those  from 
the  earlier  known  fields  were  of  high  specific  gravity  and  of 
high  asphaltic  content,  though  latterly  lighter  oils  have  been 
found.  The  sulphur  content  varies,  but  is  usually  below 
i '5  per  cent.  California  crudes  are  mostly  of  Miocene 
age. 

The  production  of  the  United  States  amounts  to  about 
65  per  cent,  of  the  world's  output. 

The  fields  of  Mexico  may  be  divided  into  two  main 
areas : — The  Gulf  zone  comprising  the  Ebano,  Panuco, 
Topila,  lyos  Naranjos,  Potrero,  and  Alamo  fields;  the 
southern  zone  comprising  the  Tehuantepec  and  Tabasco 
districts.  Production,  however,  practically  all  comes  from 
the  Gulf  zone. 

Two  types  of  crude  are  found  :  (a)  a  light  crude  of  a 
mixed-base  type,  containing  paraffin  wax  and  asphalt, 
and  a  heavy  asphaltic  type.  These  crudes  resemble  each 
other  in  that  their  volatile  constituents  are  composed 
mostly  of  hydrocarbons  of  the  paraffin  series.  They  are 
very  rich  in  sulphur,  containing  up  to  about  5  per  cent. 

I/ight  Mexican  crude  (sp.  gr.  0*925)  yields  about  15  per 
cent,  of  benzine,  7  per  cent,  of  kerosene,  gas  oil  and  lubricating 
oils  of  good  quality,  and  asphalt  or  coke. 

(b)  A  heavy  crude  of  high  specific  gravity  (about  0-980), 
which  yields  only  a  small  percentage  of  benzine.  This 
yields  excellent  asphalts  of  various  grades  and  heavy  liquid 
fuels. 

The  oils  of  Venezuela  are  also  of  high  specific  gravity 
and  of  the  asphalt-base  type ;  they  yield  only  small  quantities 
of  benzine  and  kerosene,  and  are  used  mainly  for  liquid 
fuel.  They  contain  about  2  per  cent,  of  sulphur. 

Trinidad  produces  a  considerable  quantity  of  crude 
petroleum  apart  from  that  of  asphalt  from  the  famous  lake. 
The  crude  oils  are  of  the  naphthene-base  type,  those  from 
the  deeper  sands  being  of  lower  specific  gravity  than  those 
from  the  shallower  strata.  Mixed-base  oils  have  also  been 
found. 


64      PETROLEUM  AND  ALLIED  INDUSTRIES 

The  production  of  crude  petroleum  has  never  reached 
a  high  figure  in  Canada,  though  great  efforts  have  been  made 
to  encourage  the  industry.  Several  small  fields  in  Ontario, 
e.g.  those  of  Oil  Springs  and  Petrolia,  have  already  passed 
their  zenith.  The  oils  are  similar  to  those  of  Ohio,  containing 
about  i  per  cent,  of  sulphur.  They  consist  for  the  most 
part  of  saturated  paraffins,  but  contain  hydrocarbons 
relatively  poorer  in  hydrogen  in  the  higher  fractions* 

Very  large  deposits  of  asphaltic  sands  (usually  wrongly 
termed  tar-sands)  are  found  in  Northern  Alberta,  outcropping 
on  the  banks  of  the  Athabasca  and  other  rivers  (S.  C.  Klls, 
"  Bituminous  Sands  of  Northern  Alberta,"  Dept.  of  Mines, 
Canada).  These  sands  contain  from  7  to  20  per  cent,  of 
soft  asphalt  (Krieble  and  Seyer,  /.  Am.  Chem.  Soc.,  1921, 

P-  1337)- 

Peru  produces  an  oil  of  naphthene-base  type,  in  consider- 
able quantities. 

The  Argentine  Republic  is  developing  a  crude  oil 
production  from  four  distinct  fields.  The  oils  are  similar 
in  character  to  those  of  Peru. 

Brazil  has  potential  areas  which  have  not  yet  been 
developed,  and  Bolivia  and  Colombia  have  so  far  received 
little  attention. 

The  country  which  has  played  the  second  most  important 
part  in  the  development  of  the  petroleum  industry  is  Russia. 

The  two  chief  oil-producing  areas  are  the  Caucasus  and 
the  Ural  Caspian.  The  oils  are  mostly  of  Miocene  age. 

The  production  of  the  Russian  fields  from  1910  to  1916 
was  at  the  rate  of  10,000,000  tons  per  annum.  The  present 
disturbed  political  condition  of  the  country  (1921)  has 
caused  a  reduction  in  output  to  about  one-third  of  this 
figure. 

The  oils  from  the  Balachany,  £aboontje,  Romany, 
Surachany,  and  Bibi-Eibat  fields  contain  little  or  no 
paraffin  wax,  and  are  composed  largely  of  hydrocarbons  of 
the  naphthene  type.  They  yield  good  lubricating  oils  of 
low  cold  test,  and  good  non- viscous  liquid  fuels. 

The  Grosny   fields   produce  crudes  of   two  types,  the 


OCCURRENCE   OF   CRUDE  OIL  65 

one  almost  free  from  paraffin,  the  other  relatively  rich  (about 
5  per  cent.).  These  crudes  are  also  rich  in  naphthenes  and 
contain  aromatic  hydrocarbons  in  small  quantities. 

The  Maikop  fields  3'ield  crudes  rather  richer  in  volatile 
constituents  than  those  of  the  other  Russian  fields.  The 
content  of  paraffin  wax  is  low  (about  0-5  per  cent.),  and 
aromatic  hydrocarbons  are  present. 

Rumania  possesses  several  important  fields  which  yield 
several  types  of  oil.  These  crudes  generally  consist  of  hydro- 
carbons of  the  paraffin,  naphthene,  and  aromatic  series, 
with  small  proportions  of  terpenes.  The  presence  of  aromatic 
hydrocarbons  lowers  the  burning  quality  of  the  kerosenes. 

The  crudes  of  Bustenari,  Campina,  Baicoi,  and  Tzintea 
contain  paraffin  wax  in  quantities  up  to  7  per  cent. 

The  crude  oils  of  Galicia  are  intermediate  in  character 
between  those  of  East  North  America  and  of  the  Russian 
Caucasus.  Those  of  Bast  Galicia  contain  paraffin  wax  up 
to  12  per  cent.,  those  of  the  West  are  nearly  paraffin-free. 
They  are  usually  practically  free  from  sulphur.  They  are  of 
Cretaceous,  Eocene  and  Oligocene  age. 

There  are  fields  of  relatively  minor  importance  in  Alsace 
(Pechelbronn) .  Oil  has  been  found  also  in  Italy,  France, 
Spain,  and  Greece.  It  is  of  particular  interest  to  note  that 
the  test  well  recently  put  down  in  England  (Derbyshire) 
has  produced  several  hundred  tons  of  a  remarkable  oil. 

The  Derbyshire  (Hardstoft)  crude  is  of  low  sp.  gr.  0*823, 
greenish  brown  in  colour  with  marked  fluorescence.  It 
yields  17  per  cent,  of  motor  spirits  and  30  to  40  per  cent, 
of  excellent  kerosene  (0785  sp.  gr.).  The  residual  oil  after 
removal  of  benzine,  kerosene,  and  gas  oil  is  a  cylinder  oil  of 
remarkable  quality,  containing  no  asphaltic  matter,  similar 
in  properties  to  a  Pennsylvanian  filtered  cylinder  oil.  The 
crude  contains  also  about  3!  per  cent,  of  paraffin  wax. 

In  Asia  important  oil-fields  have  been  exploited  in 
Persia,  Burmah,  and  the  Dutch  East  Indies.  Less 
important  fields  exist  in  Japan  and  Assam.  Large  fields 
probably  exist  in  Mesopotamia,  and  various  parts  of  Siberia, 
but  these  have  not  yet  been  exploited. 

P.  5 


66      PETROLEUM  AND  ALLIED  INDUSTRIES 

The  crude  oils  of  Persia  consist  of  hydrocarbons  of 
the  paraffin  series,  with  smaller  quantities  of  naphthenes. 
Aromatic  hydrocarbons  are  also  present.  They  contain 
also  sulphur  compounds.  They  are  rich  in  volatile  fractions, 
yielding  20  per  cent,  or  more  of  motor  spirits. 

The  Burmah  crude  oils  are  rich  in  paraffin  wax.  They 
consist  of  hydrocarbons  of  the  paraffin  series,  with  members 
of  the  naphthene  series  and  aromatics  also  present  in 
considerable  proportions. 

The  potentialities  of  Mesopotamia  as  an  oil-producing 
country  are  undoubtedly  great,  but  have  not  yet  been 
adequately  examined.  Oil  is  produced  in  trifling  quantities 
near  Mosul  and  at  Mandali  on  the  Persian  frontiers.  The 
oil  is  similar  to  the  crudes  of  Mexico  in  character,  and  is 
rich  in  sulphur  compounds. 

In  the  Dutch  East  Indies  many  important  fields  are 
found.  North  and  South  Sumatra  produce  light  oils,  very 
rich  in  benzine  and  kerosene  fractions.  Those  of  North 
Sumatra  are  of  paraffin-base,  those  of  the  South  of  asphaltic- 
base.  Both  types  contain  appreciable  percentages  of 
aromatics  and  considerable  percentages  of  naphthene 
hydrocarbons.  Oils  of  very  varying  character  are  found  in 
Java.  The  fields  of  East  Borneo  (Koetei)  produce  three 
types  of  crude,  heav}'  asphalt,  light  asphalt,  and  paraffin 
wax  base  oils.  The  crudes  of  the  Koetei  field  are  remarkably 
rich  in  aromatic  hydrocarbons,  as  much  as  40  per  cent, 
being  found  in  the  volatile  fractions  of  the  crude.  Those  of 
the  Tarakan  field  are  paraffin-free,  as  are  also  those  of  the 
Sarawak  fields.  These  latter  are  very  rich  in  hydrocarbons 
of  the  naphthene  series. 

Japan  possesses  several  small  fields  which  yield  oils 
of  varying  character. 

Africa  has  up  to  the  present  only  one  producing  field, 
that  of  Egypt  on  the  coast  of  the  Red  Sea.  Preliminary 
work  is,  however,  being  carried  on  in  Algeria. 

The  Egyptian  fields  yield  heavy  oils  of  mixed-base 
type.  They  contain  only  a  small  percentage  of  benzine,  and 
after  topping  this  off  the  residue  is  an  oil  of  high  viscosity. 


OCCURRENCE   OF  CRUDE  OIL  67 

The  presence  of  paraffin  wax  gives  the  residue  a  high  setting 
point.  Sulphur  is  contained  in  the  crude  oil  to  the  extent 
of  2  or  3  per  cent. 

In  Australasia  no  oil-fields  are  as  yet  developed.  Oil 
has,  however,  been  found  in  Taranaki,  New  Zealand. 

In  the  island  of  Papua  exploitation  work  is  going  on. 

The  foregoing  is  merely  a  very  condensed  summary  of 
the  most  important  fields  in  active  exploitation.  Space 
does  not  permit  of  reference  to  the  numerous  localities  where 
crude  oil  in  small  quantities  has  been  obtained. 

It  will  be  seen  from  the  foregoing  that  crude  oils  from 
different  sources  exhibit  a  great  diversity  of  character,  both 
as  regards  their  physical  constants  and  chemical  constitution. 
No  scientific  system  of  classification  has  as  yet  been  evolved, 
and  this  will  not  be  possible  until  a  great  deal  more  is  known 
about  the  chemical  constitution  of  their  components. 

The  colour  of  crude  oil  ranges  from  practically  colourless 
in  the  case  of  the  so-called  white  oils,  which  are  naturally 
filtered  oils  of  rare  occurrence,  through  shades  of  brown  and 
greenish  brown  or  black  of  varying  transparency,  to  the 
deep  black  of  asphaltic  heavy  oils  such  as  those  of  Mexico. 

The  specific  gravity  varies  from  as  low  as  0760  in  the  case 
of  some  of  the  very  volatile  oils  of  Rumania  and  Pennsyl- 
vania, to  nearly  rooo  in  the  case  of  some  heavy  Mexican  oils. 

The  viscosity  varies  from  that  of  oils  as  limpid  as  ordinary 
kerosene  to  that  of  semi-solid  asphalts. 

The  chemical  properties  show  similar  variation. 

The  carbon  percentage  ranges  from  80  to  87,  the  hydrogen 
from  9*6  to  14*5.  The  ratio  carbon/hydrogen  from  5*6  in 
the  case  of  the  volatile  oils  of  high  paraffin  content  to  8'0  or 
more  in  the  case  of  heavy  asphaltic  oils. 

The  yield  of  commercial  products  also  varies  enormously, 
lyight  oils  containing  50  per  cent,  or  more  of  benzine  are 
known,  and  heavy  oils  containing  no  benzine  or  kerosene 
fractions  whatever.  Great  variation  is  often  shown  by  the 
crude  oils  from  a  particular  field,  so  that  without  going 
into  very  great  detail  no  general  summary,  other  than  one 
very  rough,  as  given  above,  is  possible. 


68      PETROLEUM  AND  ALLIED  INDUSTRIES 

The  world's  output  of  crude  oil  for  1920,  as  contributed 
by  various  countries,  was  as  follows  : — 

United  States. .          . .  443,402,000  brls.,  i.e.  64-4  per  cent. 

Mexico             . ,          . .  159,800,000      „        „    23-2 

Russia             . .          . .  30,000,000      „        „     4-36 

Dutch  East  Indies     . .  16,000,000     ,, 

Burmah           . .          . .  8,500,000     ,, 

Rumania         . .          . .  7,406,318     ,, 

Persia 6,604,734     „ 

Galicia. .          . .          . .  6,000,000     ,, 

Peru     . .          . .          . .  2,790,000     ,, 

Japan  (incl.  Formosa)  2,213,083     ,, 

Trinidad          . .          . .  1,628,637     ,, 

Argentine        . .          . .  1,366,926 

Egypt 1,089,213     „ 

France. .          . .          . .  700,000     ,, 

Venezuela        . .          . .  500,000     ,, 

Canada            . .          . .  220,000     „ 

Germany         . .          . .  215,340     ,, 

Italy 38,000     ,, 


688,474,251      „ 

The  United  States,  Mexico,  and  Russia  thus  at  present 
produce  over  90  per  cent,  of  the  world's  output. 

The  estimated  production  for  1922  is  760,000,000 
barrels. 


GENERAL   REFERENCES   TO    PART    III.,    SECTION   A. 

Bacon  and  Hamor,  "  American  Petroleum  Industry,"  vol.  i.  McGraw- 
Hill,  New  York. 

Cadman,  Sir  John,  "  Oil  Resources  of  the  British  Empire."  J.R.S.A., 
July  30,  1920. 

Emmons,  "  Geology  of  Petroleum."     McGraw-Hill,  New  York. 

Engler-Hofer,  "  Das  Erdol,"  vols.  I  and  2.     Hirzel,  Leipzig. 

Redwood,  "  Treatise  on  Petroleum,"  vol.  I.     Griffin. 

"  Monograph  on  Petroleum,"  Imperial  Institute.     J.  Murray.     1921. 


SECTION  B.— DRILLING    AND    MINING 
OPERATIONS 

SEVERAL  methods  of  drilling  are  employed  in  the  petroleum 
industry,  the  choice  of  the  particular  method  in  any  one 
case  depending  on  various  factors,  such  as  the  depth  of  the 
well  (500  feet  in  Ontario,  4000  or  more  in  Galicia  or  Cali- 
fornia), the  nature  of  the  strata  to  be  penetrated,  and  the 
amount  of  water  present  or  available. 

The  methods  employed  may  be  classified  into  three 
groups — • 

(a)  Abrasion  or  core  drill  methods. 

(b)  Percussion  methods. 

(c)  Hydraulic  rotary  methods. 

(a)  Core  drill  methods,  being  slow  and  expensive, 
are  seldom  used  except  for  prospecting  or  test  holes.  In 
hard  formations  a  complete  core  of  the  material  drilled  through 
can  be  obtained,  and  this  may  afford  valuable  geological 
data,  such  as  the  dip  of  the  strata,  and  fossils  intact  and 
unbroken. 

The  tool  used  is  a  circular  shoe  or  bit  attached  to  the 
end  of  a  hollow  tube  wliich  is  rotated.  The  lower  end  of  this 
shoe  may  be  either  (i)  set  with  diamonds,  (2)  cut  into  teeth 
somewhat  like  a  saw  (calyx),  or  (3)  plain,  revolving  on  a 
number  of  chilled  shot,  placed  in  the  hole. 

The  diamond  drill  was  first  used  in  1863.  The  calyx 
method  was  developed  in  1873,  and  the  chilled  shot  method 
later.  By  these  methods  cores  up  to  15  inches  diameter 
may  be  obtained.  When  using  such  drills  a  stream  of 
water  is  pumped  down  the  hole  to  remove  the  abraded 
material. 

69 


70      PETROLEUM  AND  ALLIED  INDUSTRIES 

(b)  Percussion  methods  are,  however,  most  generally 
used. 

Percussion  methods  may  be  classified  into-1— 

(1)  Cable  tool  systems. 

(2)  Pole  tool  systems. 

Various  sub-divisions  of  these  systems  exist,  differing  from 
each  other  in  details  only.  For  example,  in  the  Canadian 
system  ash  poles  are  used,  in  the  Galician  light  rods  of  steel. 

For  any  system  of  drilling  a  derrick  is  required,  but  those 
used  in  the  various  systems  differ  considerably  in  detail, 
being,  however,  similar  in  fundamental  points.  Space  will 
not  permit  of  a  detailed  description  of  the  various  types. 
For  this,  the  reader  must  be  referred  to  any  of  the  standard 
works  on  petroleum  mining,  such  as  that  of  Beeby  Thompson. 

The  type  of  derrick  used  depends  on  the  locality,  on 
the  nature  of  the  strata  and  the  depth  to  which  the  well  is 
to  be  bored.  Those  used  in  the  Ontario  fields,  where  the 
wells  are  only  a  few  hundred  feet  in  depth,  often  consist 
merely  of  three  poles  fastened  together  at  the  top  so  as  to 
make  a  tripod. 

For  such  shallow  wells  a  portable  drilling  machine  is  often 
employed.  Derricks  are  often  constructed  of  timber  cut 
locally,  but  where  timber  is  scarce  steel  is  often  used. 

The  standard  derrick  which  is  largely  employed  is  built 
up  of  four  legs  braced  together  (Fig.  7).  At  the  top  is  placed 
the  "  crown  block  "  (i),  which  carries  the  crown  pulley,  over 
which  the  drilling  cable  passes.  At  the  side  of  the  derrick 
far  from  the  engine  stand  the  "  bull  wheels  "  (2).  These 
consist  of  a  drum  on  which  the  drilling  cable  is  wound, 
attached  to  a  wrheel  at  either  side.  The  wheel  on  one  side 
acts  as  a  driving  wheel,  being  grooved  to  receive  the  driving 
belt,  that  on  the  other  side  is  fitted  with  a  steel  band  brake. 

At  the  opposite  side  of  the  derrick  is  set  the  "  samsou 
post  "  (3),  which  carries  the  "  walking  beam  "(4).  One 
end  of  the  walking  beam  is  connected  by  a  rod  called  the 
"  pitman  "  (5)  to  the  crank  of  the  "  jack  "  or  "  band 
wheel  "  (6).  This  band  wheel  is  driven  by  the  engine  and 


DRILLING  AND  MINING  OPERATIONS       71 

transmits  power  to  the  bull  wheels  by  means  of  a  belt  or 
"  bull  rope."  The  other  end  of  the  walking  beam  supports 
the  drilling  cable. 

Just  behind  the  band  wheel  the  "sand  reel"  (7)  is 
placed.  This  is  carried  on  a  movable  axis  so  that  it  can  be 
driven  from  the  band  wheel  by  a  friction  pulley.  A  light 


FIG.  7. — A  drilling  rig. 

cable  passes  from  the  sand  reel  over  a  light  pulley  at  the 
top  of  the  derrick,  and  is  used  for  raising  and  lowering 
a  sand  pump  for  cleaning  out  the  hole  during  drilling 
operations. 

Derricks  used  for  deep- well  drilling  are  often  140  feet 
high,  the  great  height  allowing  several  lengths  of  casing 
to  be  hauled  up  without  disconnecting. 


72      PETROLEUM  AND  ALLIED  INDUSTRIES 


The  drilling  engine  is  controlled  by  a  "  telegraph  cord  " 
and  reversing  lever  extending  into  the  derrick.  Steam  is 
supplied  from  a  vertical  boiler  usually  of  about  20  to  40  h.p. 
placed  some  little  distance  away. 

The  complete  set  of  drilling  tools  is  usually  termed  a 
"  string."  It  consists  of  the  following  :  "  rope  socket," 
"  sinker  bar,"  "  jars/'  "  auger  stem,"  and  "  bit." 

The  rope  socket  is  a  device  for  attaching  the  drilling 
cable  to  the  tools  ;  the  sinker  bar  is  a  long  heavy  steel  bar, 
which  merely  functions  as  a  weight.  It  is  often  omitted, 

but  is  sometimes  placed 
below  the  jars.  The 
jars  are  practically  a 
pair  of  interlocking 
links.  They  have  a 
play  or  lost  motion  of 
about  2  feet. 

When  the  links  of 
the  jars  engage  on  the 
upstroke  a  sudden  jerk 
is  given  to  the  bit 
which  loosens  it,  should 
it  tend  to  stick.  When 
drilling,  the  cable 
should  be  adjusted  so 
that  the  upper  link  of 
the  jars  does  not  de- 
scend far  enough  to 
strike  the  lower  link.  This  can  easily  be  adjusted  by  an 
experienced  driller  by  feeling  the  vibration  transmitted 
through  the  drilling  cable. 

The  auger  stem  is  a  long  cylindrical  piece  of  steel.  It 
adds  weight  to  the  bit  and  helps  to  keep  the  hole  straight. 

Many  types  of  bit  are  used  according  to  the  nature 
of  the  rock  through  which  the  hole  must  be  drilled.  The 
usual  type  is  chisel  shaped,  the  diameter  of  the  cutting  edge 
being  larger  than  that  of  the  stem  (Fig.  8). 

Drilling  tools  are  usually  fitted  with   a  conical   screw 


FIG.  8. — Types  of  drilling  bits. 


DRILLING  AND  MINING  OPERATIONS       73 

which  fits  into  a  corresponding  socket  on  the  lower  end  of 
the  auger  stem.  The  jars,  sinker  bar,  and  drilling  poles 
(if  used)  are  all  so  fitted.  They  are  screwed  together  by 
means  of  a  very  powerful  wrench  or  jack  operated  on  the 
derrick  floor. 

The  first  stage  in  the  actual  drilling  of  a  well  is  the 
insertion  of  the  "  conductor."  This  is  usually  an  ordinary 
steel  drive-pipe,  10  to  30  feet  long. 
This  must  be  very  carefully  fixed  in  a 
vertical  position  as  it  serves  to  guide 
the  first  lengths  of  casing  fixed  into 
the  well. 

Owing  to  the  length  ofc  a  complete 
string  of  tools,  drilling  cannot  be 
started  in  the  normal  manner  used 
when  the  hole  is  deeper.  The  method 
termed  "  spudding "  is  therefore 
adopted.  A  bit  and  auger  stem  are 
connected  to  the  cable  and  lowered 
into  the  hole  till  they  touch  bottom, 
and  the  cable  is  fixed.  A  "  spudding 
shoe  "  is  then  fixed  on  to  the  cable 
near  the  bull  wheel  and  connected 
by  a  "  jerking  "  rope  to 
the  crank  of  the  band 
wheel. 

As  the  crank  re- 
volves, the  bull  wheels 
being  fixed,  the  cable  is 
drawn  forward  and  then 
released,  an  up  -  and  - 
down  motion  thus  being  transmitted  to  the  tools  (Fig.  9). 

As  the  hole  is  bored  detritus  rapidly  accumulates  and 
must  be  removed  from  time  to  time.  This  is  effected  by 
raising  the  tools  from  the  well  and  lowering  the  "  sand  pump  " 
or  "  baler."  This  consists  merely  of  a  length  of  tubing  with  a 
valve  at  the  bottom  opening  inwards,  which  is  operated  by 
a  projecting  stem.  As  this  stem  strikes  the  bottom  of  the 


FIG.  Q. — Arrangement  for  spudding. 


74      PETROLEUM  AND  ALLIED  INDUSTRIES 

hole  the  valve  opens  allowing  the  muddy  debris  to  enter. 
As  soon  as  the  sand  pump  is  raised  from  off  the  bottom  of 
the  well  the  valve  naturally  closes  again,  retaining  the 
contents,  which  are  discharged  into  a  drain  at  the  top  of 
the  well  by  means  of  lowering  the  sand  pump  on  to  the 
ground,  the  valve  being  thereby  opened.  The  hole  is 
usually  drilled  by  spudding  in  this  way  to  a  depth  of  about 
150  feet  or  so.  The  string  of  tools  is  then  attached  to  the 
"  walking  beam  "  by  means  of  the  "  temper  screw,"  an 
arrangement  whereby  the  cable  can  be  let  out  a  few  inches 
at  a  time  as  drilling  proceeds. 

Drilling  is  then  carried  on  by  means  of  the  walking 
beam,  a  manilla  cable  being  often  used.  For  great  depths, 
however,  this  is  usually  replaced  by  a  steel  cable. 

In  the  case  of  hard  strata  the  walls  of  the  well  require 
no  protection,  but  when  the  strata  are  soft  or  yielding 
the  well  must  be  lined  with  "  casing  "  in  order  to  prevent 
the  caving  in  of  the  well.  lycngths  of  casing  or  drive-pipe 
are  lowered  or  forced  down  into  the  well  following  the 
drill,  the  lengths  of  pipe  being  screwed  together.  As  an 
indefinite  length  cannot  be  sunk  owing  to  friction  it  is  usual 
to  start  the  well  with  a  tool  of  large  diameter,  and  to 
insert  large  diameter  drive-pipe  or  casing,  driving  this  to  as 
great  a  depth  as  the  friction  will  allow. 

The  initial  diameter  of  the  well  depends  on  the  depth 
to  which  it  is  to  be  drilled  and  on  the  nature  of  the  strata. 

Casing  up  to  diameters  of  14  inches  or  even  more  is  in 
general  use,  but  in  Russia  pipes  of  larger  diameter,  con- 
structed of  plates  riveted  together,  are  often  used.  Casings 
of  several  different  types  are  used  dependent  on  local 
conditions. 

The  lower  end  of  the  string  of  casing  is  usually  armed 
with  a  "  casing  shoe,"  a  ring  with  a  sharp  edge.  The  casing 
can  be  "  set  "  by  driving  this  into  any  suitable  stratum 
when  the  casing  cannot  well  be  driven  to  a  greater  depth. 

To  enable  the  casing  to  sink  in  the  well  "  under-reaming  " 
is  often  necessary.  This  is  carried  out  by  a  special  under- 
reamer,  which  is  a  tool  with  an  expansible  bit,  so  that  the 


DRILLING  AND  MINING  OPERATIONS       75 

cutting  edges  of  the  bit  can  be  squeezed  together  to  allow 
of  its  passage  through  the  casing.  When  it  reaches  a  point 
below  the  casing  the  cutting  edges  are  forced  apart  by 
means  of  powerful  springs,  so  that  a  hole  of  larger  diameter 
than  the  casing  can  be  bored. 

Casing  performs  a  further  and  very  important  function 
in  the  shutting  off  of  water. 

Water-bearing  levels  are  often  encountered  in  boring 
a  well.  If  these  are  not  adequately  sealed  up  or  shut 
off,  water  will  descend,  perhaps  even  behind  the  casing, 
to  lower  levels  and  may  enter  the  oil-producing  layer,  thus 
spoiling  not  only  that  particular  well  but  probably  others  in 
the  same  stratum.  The  adequate  shutting  off  of  water 
is  thus  of  the  greatest  importance.  In  many  countries 
this  is  recognized,  and  regulations  are  in  force  to  ensure 
that  this  is  properly  carried  out. 

The  process  most  generally  used  is  that  of  "  cementing." 
The  lower  edge  of  the  outside  string  of  casing  is  set  in 
position,  usually  in  an  impervious  layer.  Cement  is  then 
forced  down  to  this  point,  between  the  outer  and  inner 
casing ;  or  the  inner  casing  may  be  cut  off  just  above  this 
point  and  the  space  between  the  two  filled  by  cement,  the 
well  being  plugged  at  this  point  temporarily  to  allow  of 
this  being  done.  A  description  of  the  methods  of  shutting 
off  of  water  from  oil  wells  is  outside  the  scope  of  this  work. 
Detailed  descriptions  may  be  found  in  such  works  as  Beeby 
Thompson's  "  Oil  Fields  of  Russia  "  and  in  the  various 
bulletins  published  by  the  U.S.A.  Bureau  of  Mines  on  this 
subject. 

When  a  string  of  casing  has  been  set,  drilling  is  con- 
tinued with  a  bit  of  smaller  diameter,  this  being  followed 
up  by  a  string  of  casing  of  smaller  diameter,  which  of  course 
must  extend  to  the  top  of  the  well.  This  second  string  of 
casing  is  forced  down  as  far  as  possible  and  eventually  set, 
the  drilling  being  then  continued  with  another  bit  of  still 
smaller  diameter. 

A  finished  well  may  thus  have  a  diameter  of  16  inches 
or  more  at  the  top  and  4  inches  at  the  bottom,  and  may  have 


76      PETROLEUM  AND  ALLIED  INDUSTRIES 


several  strings  of  casing  extending  to  successively  greater 
depths,  arranged  one  inside  the  other  in  telescope  fashion 
(Fig.  10). 

It  is  not,  however,  necessary  that  each  string  of  casing 
should  extend  to  the  surface  after  the  well  has  been  com- 
pleted and  found  to  be  successful.  The  upper  or  free 
portions  of  the  inner  strings  may  be  cut  off  by  a  special 
tool  lowered  into  the  well,  and  removed,  the  points  at  which 

one  string  of  casing  is  set  and 
the  next  smaller  size  starts 
being  well  sealed  up  by 
cementing. 

In  drilling  wells  many  diffi- 
culties are  usually  encoun- 
tered, and  many  ingenious 
devices  are  adopted  for  over- 
coming these  difficulties. 

Boulders  are  sometimes 
encountered  in  a  clay,  and  if 
large  may  easily  be  mistaken 
for  a  bed  of  hard  rock.  These 
are  usually  broken  to  pieces 
and  removed  sometimes  by  the 
aid  of  explosives.  When  drill- 
ing through  highly  inclined 
strata  there  is  often  a  tendency 
for  the  drill  to  deflect  to  one 
side  especially  when  a  hard 


FIG.  ro. — Strings  of  casing  in 
a  well. 


stratum  is  encountered,  tending  to  follow  the  dip  of  the  strata 
and  so  causing  the  hole  to  diverge  from  the  vertical.  This  can 
be  avoided  by  slow  and  careful  drilling  with  a  long  auger  stem. 
Dry  sands  also  cause  trouble,  as  they  absorb  water,  so 
that  very  large  quantities  would  need  to  be  pumped  into  the 
hole.  If  drilling  were  attempted  without  water  the  bits 
would  overheat  and  the  sand  would  impede  the  action  of 
the  drill.  In  such  a  case  mud  is  pumped  into  the  hole. 
This  fills  up  the  pores  of  the  sand  by  a  puddling  action  and 
allows  drilling  to  proceed. 


DRILLING  AND  MINING   OPERATIONS       77 

"  Spalls  "  of  rock  or  loose  stones  may  fall  from  the 
sides  on  top  of  the  bit  and  jam  it  so  that  it  cannot  be  moved. 
These  may  then  require  drilling  out  by  a  smaller  bit,  to 
render  the  large  bit  free  again. 

Soft  muds  and  clays  are  difficult  to  deal  with  as  they  fill 
up  the  hole  as  soon  as  it  is  formed.  In  such  cases  drilling 
must  be  quickly  carried  out  and  the  casing  must  closely 
follow  the  bit.  Cavities  are  sometimes  found,  particularly 
in  limestone  strata. 

Quicksand  is  sometimes  encountered,  and  if  the  hydro- 
static pressure  is  great  this  may  quickly  flow  into  the  hole 
so  as  to  engulf  the  tools,  making  their  withdrawal  very  diffi- 
cult. A  quicksand  can,  however,  usually  be  driven  through 
by  keeping  a  good  head  of  water  in  the  well,  so  as  to  overcome 
the  hydrostatic  head  of  the  sand.  In  some  cases  cement 
may  be  introduced  into  the  well  so  as  to  percolate  into  the 
sand  and  form  a  solid  block  which  may  be  subsequently 
drilled  through.  An  ingenious  method  of  drilling  through 
quicksand  was  devised  by  Poelsch  in  1883.  He  drove 
pipes  into  the  quicksand  and  circulated  cold  brine  through 
them,  thus  freezing  the  sand  into  a  solid  mass  through  which 
boring  could  be  conducted  in  the  usual  way.  The  need 
for  such  methods,  however,  very  rarely  arises. 

A  variation  of  the  percussion  system  of  drilling  as  described 
above  is  the  Water  flush  method.  The  cable  is  replaced 
by  a  string  of  pipes  screwed  together,  through  which  water 
can  be  pumped,  emerging  through  two  holes  in  the  upper 
part  of  the  bit.  The  stream  of  water  carries  up  the  debris 
to  the  surface,  thus  obviating  the  need  for  sand  pumping. 

(c)  The  Hydraulic  rotary  method,  which  was  first 
used  in  the  famous  Spindle  Top  field  of  Texas,  has  now 
come  into  general  use,  especially  in  cases  where  soft 
materials  are  to  be  penetrated. 

The  plant  consists  of  a  heavy  revolving  table  driven 
by  cog  gear  and  a  chain  and  sprocket  wheel.  The  drill 
pipe  passes  through  the  centre  of  the  table,  being  gripped  by 
clamps  which,  however,  are  arranged  so  as  to  allow  the 
piping  to  be  gradually  lowered.  The  drill  pipe  is  usually 


78      PETROLEUM  AND  ALLIED  INDUSTRIES 
made  of  heavy  4-inch   piping  and  carries  a  fish-tail  drill 


FIG.  ii. — Arrangement  for  drilling  by  rotary  method. 

at  its  lower  end.     Water  is  supplied  to  the  upper  projecting 
end  of  the  pipe  by  a  flexible  hose  and  swivel  joint.     As  the 


DRILLING  AND  MINING  OPERATIONS       79 

drill  is  rotated  water  is  continuously  pumped  down  the 
pipes,  and  emerges  through  holes  in  the  bit,  carrying  the 
detritus  upwards  through  the  hole.  The  detritus  is  allowed 
to  settle  out  of  the  water,  and  this  can  then  be  used  again. 
In  fact,  muddy  water  is  often  used  in  order  to  clog  up  the 
pores  of  any  sand  which  is  being  penetrated  so  as  to  avoid 
loss  of  water.  In  drilling  through  clay,  however,  clear  water 
is  used.  The  well  often  requires  no  casing,  as  the  mud 
puddles  its  sides  so  that  the  material  is  able  to  stand  up 
alone. 

In  this  system  of  drilling  it  is  essential  that  the  operation 
be  continuous.  If  it  be  stopped  then  the  accumulation  of  mud 
will  jam  up  the  bit  and  drill  pipes.  A  recent  improvement 
is  the  Sharp-Hughes  patent  cone  bit.  This  consists  of  two 
hard  steel-toothed  cones  which  can  revolve  on  bearings 
supplied  with  lubricating  oil  by  a  special  pipe  fitted  inside 
the  drill  tube.  The  use  of  this  bit  enables  the  rotary  outfit 
to  be  used  for  drilling  through  hard  rock  also. 

The  hydraulic  rotary  can  penetrate  soft  strata  at  a 
great  speed.  In  Texas  wells  have  been  drilled  at  the  rate 
of  30  feet  an  hour. 

The  fact  that  the  mud  puddles  up  the  sand  is  a  disad- 
vantage in  drilling  in  an  area  the  underground  geology  of 
which  is  not  known,  as  it  is  possible  to  pass  through  an  oil 
sand  without  noticing  it,  if  the  hydraulic  pressure  of  the 
water  column  in  the  well  is  greater  than  that  of  the  oil  in 
the  sand. 

Fishing. — In  spite  of  all  precautions  tools  occasionally 
become  detached ;  a  cable  may  break,  tools  may  become 
unscrewed,  or  the  screw  pins  may  break.  The  difficulties 
of  extracting  such  lost  tools,  "  fishing  "  as  this  is  called,  are 
great. 

In  the  first  case  some  information  must  be  obtained 
as  to  the  position  of  the  tools  in  the  hole.  This  is  often 
obtained  by  lowering  down  a  special  tool  with  a  bell-shaped 
opening  filled  with  wax.  An  impression  of  the  top  of  the 
lost  tools  may  be  so  obtained  and  a  special  fishing  tool  may 
then  be  designed  to  catch  hold  of  them.  Many  ingenious 


80      PETROLEUM  AND   ALLIED  INDUSTRIES 


tools  and  methods  have  been  designed  and  even  special  photo- 
graphic apparatus  has  sometimes  been  lowered  into  a  well. 

Several  standard  types  of  fishing  tools  such  as  the 
"  slip  socket  "  and  "  cable  spear  "  are  often  used.  The 
slip  socket  consists  of  a  tube  containing  two  movable  slips, 
one  on  either  side,  with  teeth  pointing 
upward.  The  apparatus  is  lowered 
over  the  lost  tools,  and  on  raising  it 
the  toothed  slips,  falling  as  low  as 
they  can  in  the  bevelled  grooves  in 
which  they  slide,  bite  into  the  tool 
and  hold  it  firmly  while  it  is  pulled  up 
(Fig.  12).  The  cable  spear  is  simply 
a  "spike"  with  barbs  pointing  up- 
wards so  as  to  engage  in  the  cable 
which  may  have  broken  and  slipped 
down  into  the  well. 

Further  trouble  may  be  encoun- 
tered by  casing  slipping  into  the  well, 
or  becoming  distorted.  For  details  of 
methods  of  dealing  with  these  various 
difficulties  reference  must  be  made  to 
one  of  the  standard  works  on  drilling. 
They  fall  outside  the  scope  of  this 
book. 

Flowing  Wells. — When  the  drill- 
ing has  been  completed  and  the  oil 
sand  reached,  the  well  may  gush,  or 
quietly  flow,  or  need  pumping,  accord- 
ing to  the  gas  pressure. 
In  Russia,  California,  and  Mexico  "  gushers  "  of  enormous 
size,  yielding  10,000  tons  or  more  per  day,  have  often  been 
struck.  Such  large  wells  frequently  get  out  of  control, 
a  large  part  of  the  oil  may  be  lost  and  much  damage  to 
surrounding  property  may  ensue. 

The  greatest  oil  well  so  far  brought  in  was  the  Potrero 
del  L,lano  No.  4  of  Mexico,  which  produced  at  one  period  at 
the  rate  of  25,000  tons  per  day. 


FIG.  12. — Slip  socket. 


DRILLING  AND  MINING  OPERATIONS       Si 

Many  wells,  under  control,  flow  for  years  at  a  continually 
decreasing  rate  owing  to  the  gradual  fall  in  gas  pressure. 
In  the  case  of  flowing  wells  the  oil  is  led  by  pipes  connected 
to  the  casing-head,  through  a  gas  separator,  if  necessary, 
to  storage  tanks. 

Methods  of  Raising  Oil. — Many  wells,  however,  do  not 
flow  but  require  pumping. 

This  is  usually  effected  : 

(a)  by  means  of  mechanically  operated  pumps, 

(b)  by  means  of  an  airlift  system,  or 

(c)  by  baling. 

(a)  The  pump  consists  of  a  working  barrel  to  the  lower 
edge  of  which  is  attached  the  suction  pipe,  on  the  upper  end 
of  which  is  the  suction  valve.     The  piston  or  plunger  of  the 
pump    is   fitted    with    several   cup-leathers,  which  expand 
against  the  walls  of  the  barrel  forming  a  tight  piston.     This 
is  necessary,  as  such  a  long  column  of  oil  requires  lifting. 
The  plunger  is  operated  by  means  of  a  cable  or  steel  rods 
attached  to  the  walking  beam. 

In  many  fields  where  the  wells  are  close  together  a  number 
of  wells  are  pumped  from  a  central  station.  An  oscillating 
wheel  or  "  jerker  "  has  attached  to  it  a  number  of  steel  rods 
or  cables  which  operate  the  pumping  jacks  at  the  various 
wells.  In  this  way  pumping  is  economically  carried  out,  as 
the  wells  can  be  so  connected  up  that  half  the  pump  rods 
are  descending  while  half  are  ascending.  In  the  Petrolia 
field  of  Canada  many  such  wells  may  be  operated  by  a 
12-h.p.  engine. 

(b)  In  some  fields  the  airlift  system  is  used.    The  opera- 
tion of  this  system  depends  on  the  aeration  of  the  column  of 
oil  in  the  well  by  means  of  a  jet  of  compressed  air  emitted 
from  the  bottom  of  a  central  tube  lowered  to  the  bottom  of 
the  well.     The  pressure  due  to  the  aerated  column  of  liquid 
must  of  course  be  less  than  the  pressure  due  to  the  previously 
existing  column  of  liquid  in  order  to  obtain  a  flow  (Stirling, 
"The  Airlift  System  of  Raising  Oil,"  J.I.P.T.,  1920,  p. 

379)- 

The  chief  advantages  of  this  system  are — 
P.  6 


82     PETROLEUM  AND  ALLIED  INDUSTRIES 

1.  Automatic  action  and  reliability. 

2.  No  moving  parts  to  get  out  of  order. 

3.  Applicability  to  oils  containing  sand  in  suspension. 

4.  Applicability  to   wells    of    small    diameter    and    to 
crooked  boreholes. 

5.  lyow  operating  costs. 

6.  Concentration    of    machinery    in    one    building    and 
transmission  of  compressed  air  with  little  or  no  loss. 

In  cases  where  the  airlift  system  cannot  be  used,  and  where 
owing  to  the  sand  content  of  the  oil  ordinary  pumping 
methods  are  inapplicable,  resort  must  be  had  to  baling.  This 
method  is  largely  used  in  Russia  and  Rumania.  The  baler 
consists  merely  of  a  long  tube  with  a  valve  at  the  bottom, 
a  sand  pump,  in  fact,  which  is  alternately  lowered  into 
and  raised  from  the  well.  Such  a  method  of  operation  is, 
of  course,  the  most  expensive. 

Another  method,  somewhat  similar  in  principle,  is  that 
known  as  swabbing.  A  string  of  tubes  fitted  with  an 
expanding  packer  is  lowered  into  the  well,  the  packer  being 
fixed  some  20  feet  or  more  from  the  lower  end  of  the 
tubes.  The  arrangement  is  then  hauled  up,  a  valve  in  the 
tubing  automatically  closing.  The  tubes  and  packer  thus 
act  as  a  piston  and  exert  a  great  suction  on  the  oil.  This 
process  is  of  great  use  also  for  cleaning  out  a  well  which  may 
have  become  clogged  with  waxy  deposit  or  sand. 

Shooting. — In  order  to  increase  the  yield  of  an  oil  well 
the  method  of  "  shooting  "  is  often  employed.  A  charge 
of  many  quarts  of  nitro-glycerine  is  lowered  in  a  canister 
into  the  well,  and  exploded  by  means  of  a  time  fuse.  The 
powerful  explosion  at  the  bottom  of  the  well  shatters  the 
rock  in  the  vicinity,  with  the  result  that  a  series  of  cracks 
radiating  from  the  well  enable  the  oil  to  flow  thereto  more 
easily,  the  daily  yield  being  thereby  often  considerably 
increased. 

A  method  of  mining  for  oil  by  means  of  shafts  and 
galleries  has  been  applied  in  the  fields  of  Pechelbronn, 
Alsace,  by  which  it  is  maintained  that  a  greater  yield  of  oil 
can  be  obtained  than  by  boring  methods  (Paul  de  Chambrier, 


DRILLING  AND  MINING  OPERATIONS       83 

J.I.P.T.,  1921,  p.  178).  The  method  in  this  particular 
area  has  proved  of  value,  but  its  application  would  appear 
to  be  limited,  especially  in  the  case  of  fields  where  the  oil  is 
found  at  great  depths  and  which  yield  oil  of  high  volatility. 
Moreover,  in  many  fields  where  the  anticline  or  dome 
structure  predominates  and  where  water  underlies  the  oil, 
the  upward  percolation  of  the  water  consequent  on  the 
gradual  removal  of  the  oil  must  remove  from  the  oil  sands 
most  of  the  oil  which  they  would  otherwise  retain. 

Oil  Well  Fires. — Oil  and  gas  wells  occasionally  catch 
fire,  owing  to  lightning,  frictional  electric  sparks,  or  careless- 
ness. Various  ingenious  methods  for  extinguishing  such 
fires  have  been  devised.  In  some  cases  they  have  been 
choked  out  by  steam,  in  others  by  the  use  of  a  foam  caused 
by  the  interaction  of  two  aqueous  solutions  liberating 
carbon  dioxide  An  ingenious  method  of  extinguishing  a 
gas- well  fire  was  recently  described  in  the  Oil  Trade  Journal, 
April,  1920.  A  package  of  dynamite  was  drawn  on  a 
suspended  cable  until  it  was  in  the  close  vicinity  of  the 
flame,  and  was  then  exploded,  the  explosion  wave  literally 
blowing  out  the  flame. 

Oil-field  Waste. — Oil-field  operations  are  unfortunately 
often  associated  with  great  waste,  both  of  material  and 
labour.  This  subject  has  recently  been  dealt  with  in  a 
paper  read  by  A.  Beeby  Thompson  before  the  Institution 
of  Petroleum  Technologists  on  November  8,  1921.  Oil-field 
waste  may  be  divided  into :  (a)  Development  waste.  Owing 
to  the  mobility  of  petroleum  a  well  put  down  on  one  lease 
may  draw  supplies  partly  from  an  adjacent  lease.  As  a 
result  of  this  an  unnecessary  number  of  wells  are  put  down 
(often  too  hurriedly)  along  the  boundary  line  between  ad- 
jacent leases,  especially  when  the  leases  are  of  small  area. 

(b)  Extraction  losses.     The  occasionally  bringing  in  of 
uncontrollable  wells  results  in  much  loss  of  both  valuable 
oil  and  gas.    Moreover,  even  with  the  most  improved  methods 
of  extraction,  a  large  proportion  of  the  oil  contained  in  a 
porous  bed  necessarily  remains  underground. 

(c)  Fuel   Waste.     Owing  partly  to   the  flexibility   and 


84     PETROLEUM  AND   ALLIED  INDUSTRIES 

fool-proofness  of  the  steam  engine,  this  is  still  the  favourite 
source  of  power,  often  in  spite  of  the  fact  that  enormous 
supplies  of  gas  are  running  to  waste.  Owing  to  fire  risks 
the  boilers  (which  are  usually  of  low  efficiency)  are  placed 
some  considerable  distance  from  the  derrick,  so  that  the 
losses  in  transmission  of  steam  (often  through  unlagged 
lines)  is  very  considerable. 

(d)  Evaporation  losses.  The  importance  of  this  is  too 
seldom  recognized.  It  has  been  calculated  that  (Wiggins, 
Pet.  Age,  1920)  the  losses  by  evaporation  in  the  Mid-Continent 
fields  of  America  amounted  to  nearly  3  per  cent,  of  the  total 
gasoline  output  of  the  United  States.  Even  in  well-designed 
storage  tanks  the  loss  by  evaporation  of  a  benzine  may 
amount  to  several  percents.  per  annum.  This  subject  is  now 
receiving  serious  attention,  insulated  tanks  have  been  tried 
and  systems  of  vapour  absorption  are  being  introduced. 


GENERAL   REFERENCES   TO   PART   III.,    SECTION    B. 

Arnold  and  Garfias,  "  The  Cementing  Process  of  excluding  Water  from 
Wells."  Technical  Paper  32,  U.S.  Bureau  of  Mines. 

C.  H.  Beal,  "  The  Decline  and  Ultimate  Production  of  Oil  Wells." 
Bulletin  177,  U.S.  Bureau  of  Mines.  Petroleum  Technology  51. 

Beeby  Thompson,  "  Petroleum  Mining."     Crosby  Lockwood. 

F.  G.  Clapp,  "  Petroleum  and  Natural  Gas  Resources  of  Canada," 
vol.  2.  Canada  Department  of  Mines. 

W.  H.  Jeffery,  "Deep  Well  Drilling."  W.  H.  Jeffery  Co.,  Toledo, 
Ohio. 

Ockenden  and  Carter,  "  Rotary  System  of  Drilling  Oil  Wells." 
J.I.P.T.,  vol.  6,  p.  249. 

Ockenden  and  Carter.  "  Plant  used  in  the  Percussion  System  of  Drilling 
Oil  Wells."  J.I.P.T.,  vol.  5,  p.  161. 


SECTION  C.— STORAGE   AND   TRANSPORT   OF 
CRUDE  OIL  AND  ITS  LIQUID  PRODUCTS 

THE  conditions  of  storage  of  crude  oil  on  the  fields  often 
leave  much  to  be  desired.  Particularly  in  the  case  of 
opening  up  of  new  fields,  when  the  probable  output  is  a 
matter  of  conjecture  only,  adequate  storage  facilities  have 
often  not  been  provided,  and  much  oil  has  in  consequence 
been  wasted.  Occasionally  exceptionally  large  gushers  are 
brought  in  and  may  get  out  of  control,  so  that  hastily 
constructed  earthen  reservoirs  are  perforce  used  for 
temporary  storage,  the  loss  by  leakage  and  evaporation  in 
such  cases  being  very  great,  especially  in  the  case  of  light 
and  volatile  crudes. 

The  practice  of  storing  oil  in  open  reservoirs,  at  one 
time  common,  when  the  volatile  fractions  were  a  drug  in. 
the  market,  is  happily  now  rare  and  need  not,  therefore,  be 
described. 

In  Canada  and  Galicia  underground  storage  tanks  are 
extensively  used.  They  are  constructed  by  excavating 
circular  holes,  lining  the  sides  with  wooden  planks  and 
puddling  behind  these  with  clay.  Wooden  roofs  covered 
with  asphalt  roofing-felt  are  used. 

Wooden  cylindrical  tanks  made  of  staves,  hooped  to- 
gether with  steel  bands,  are  still  largely  used  in  America. 
Such  tanks  are,  however,  always  of  small  capacity,  and  are 
used  merely  as  receiving  tanks  at  the  well  mouth. 

The  use  of  steel  storage  tanks  is,  however,  now  almost 
universal.  Such  tanks  are  constructed  of  various  capacities 
up  to  55,000  barrels,  i.e.  8000  tons,  sometimes  larger.  Such 
tanks  may  have  diameters  up  to  100  feet  or  more  and  usually 
range  in  height  up  to  about  36  feet. 

85 


86      PETROLEUM  AND  ALLIED  INDUSTRIES 

They  are  constructed  of  steel  plates  riveted  together, 
the  thickness  of  the  plates  diminishing  towards  the  top 
of  the  tank.  The  lowest  course  of  plates  is  riveted  to  the 
bottom  by  means  of  a  heavy  angle  iron.  The  roofs  are 
usually  of  the  self-supporting  type,  consisting  of  thin  sheet 
plates  supported  on  the  rafters  and  purlins.  Wooden  roofs 
are  sometimes  used,  but  this  is  inadvisable,  particularly  in 
areas  where  thunder-storms  are  frequent.  Good  metallic 
contact  of  the  roof  plates  with  the  side  is  of  great  importance, 
otherwise  electric  disturbances  may  cause  sparking  and  the 
loss  of  the  contents  of  the  tank  by  fire. 

Tanks  designed  for  the  storage  of  volatile  crudes  or 
distillates  should  always  be  made  gas-tight,  and  fitted  with 
some  form  of  pressure  and  vacuum  valve  (7,  Fig.  13). 


FIG.  13. — Diagrammatic  view  of  steel  tank  for  storage  of  oil. 

The  tank  must  be  fitted  with :  a  water  draw-off  valve  (i) 
at  the  bottom,  which  can  be  closed  by  an  internal  valve  ; 
one  or  more  inlet  and  outlet  pipes  situated  near  the  bottom 
of  the  tank,  and  provided  either  with  internal  valves  (2)  or 
with  a  swing  pipe  arrangement  (3). 

These  internal  valves  or  swing  pipes  are  a  necessary 


STORAGE  AND   TRANSPORT  OF   CRUDE   OIL    87 

-L 


88      PETROLEUM  AND  ALLIED  INDUSTRIES 

precaution  against  the  breaking  of  the  external  valves  and 
consequent  loss  of  oil. 

Tanks  are  further  provided  with  one  or  more  man- 
holes (4,  Fig.  ISA),  on  the  bottom  course  of  the  plates  and 
on  the  roof,  to  allow  of  entry  for  cleaning  purposes,  with 
one  or  two  "  dipping  holes  "  (5)  in  the  roof  fitted  with  plugs 
for  gauging  purposes. 

Some  form  of  water  sprinkling  arrangement  (6)  is  also 
usual,  for  cooling  the  roof  and  sides  of  the  tank  in  hot 
weather,  or  in  the  event  of  an  adjacent  tank  being  on 
fire. 

The  loss  by  evaporation  of  volatile  fractions  is  a  very 
serious  question,  which  has  in  the  past  received  far  too  little 
attention. 

Recent  tests  carried  out  in  the  United  States  (J.  H. 
Wiggins,  Petroleum  Age,  July,  1920)  have  shown  that  the 
losses,  owing  to  filling  tanks  in  the  summer  by  overshot 
connections,  may  amount  to  i  to  2\  per  cent,  a  day. 

Light  crude  oil  containing  30  per  cent,  of  benzine  was 
found  to  lose  3  per  cent,  of  its  volume  in  being  stored  in  a 
well-made  steel  tank  for  a  year.  As  the  most  volatile 
fractions  are  lost,  the  monetary  loss  amounts  to  much  more 
than  3  per  cent. 

With  well-made  tanks,  fitted  with  gas-tight  roofs,  in 
the  tropics,  the  losses  can  be  reduced  to  about  3  per  cent, 
per  annum,  but  nevertheless  usually  exceed  this  figure  even 
in  temperate  climates. 

The  chief  causes  of  loss  in  storage  are  : — 

(1)  Leakage  through  faulty  seams  ; 

(2)  Expulsion  of  air  and  benzine  vapour  when  pumping 
into  a  tank ; 

(3)  The   alternate   expulsion  of   a   mixture  of   air   and 
benzine  vapour  during  the  day  and  the  sucking  in  of  air 
during  the  night,  the  so-called  "  breathing  "  of  a  tank. 

Leakage  can  be  minimized  by  careful  construction.  The 
use  of  welded  tanks  will  doubtless  become  common  in  the 
future,  a  few  having  already  been  constructed. 

Evaporation  losses  due  to  pumping  and  breathing  cannot 


STORAGE  AND   TRANSPORT  OF  CRUDE  OIL    89 

be  entirely  avoided,  but  may  be  minimized  in  several 
ways. 

The  storage  tanks  should  always  be  painted  white. 
Some  experiments  conducted  in  Mexico  showed  that  a  loss 
of  0'59  per  cent,  per  annum  for  a  tank  painted  black,  could 
be  reduced  to  0*28  per  cent,  by  merely  painting  it  white. 

Storage  losses  may  also  be  considerably  reduced  by 
connecting  tanks  by  means  of  vapour  lines  to  a  scrubbing- 
tower,  down  which  heavy  distillate  or  gas  oil  is  trickling. 
Vapours  will  thus  be  largely  absorbed  and  may  be  recovered 
by  distillation  of  the  gas  oil.  Such  installations  are,  how- 
ever, as  yet  very  rare. 

Crude  oil  after  collection  at  a  central  tank  farm  is 
transported  to  the  refineries  by  pipe-line,  tank  car,  or  tank 
steamer. 

The  pipe- line  system  of  the  United  States  is  now  very 
extensive,  about  45,000  miles  of  transport  pipe-lines  now 
being  in  use. 

Many  other  pipe-lines  of  considerable  length,  e.g.  those 
from  the  fields  of  Rumania  to  Constanza,  and  that  from 
Baku  to  Batoum,  have  also  been  laid  down. 

These  pipe-lines,  which  are  usually  of  diameters  of  from 
4  to  12  inches,  are  laid  underground.  Pumping  stations  are 
set  up  at  intervals  along  the  line,  the  distances  between  the 
pumping  stations  being  determined  by  the  viscosity  of  the 
oil  to  be  pumped.  Pressures  up  to  800  or  900  Ibs.  per 
square  inch  are  often  employed.  In  the  case  of  very  viscous 
oils,  heating  arrangements  are  usually  installed  at  the 
pumping  stations. 

A  list  of  the  principal  pipe-lines  in  the  United  States  is 
given  in  Bulletin  No.  14  of  the  Kansas  City  Testing 
laboratory. 

The  rate  of  flow  of  liquid  moving  through  a  pipe-line 
depends  on  various  factors :  the  pressure  at  which  the 
liquid  is  fed  in  by  the  pumps,  the  viscosity  of  the  oil,  and 
the  diameter,  length,  nature  of  internal  surface,  and  number 
and  nature  of  bends  of  the  pipe-line. 

A  discussion  of  this  subject  is  to  be  found  in  the  J./.P.T., 


90      PETROLEUM  AND   ALLIED  INDUSTRIES 

vol.  2,  p.  45,  Glazebrook,  Higgins,  and  Pannel,  and  tables 
for  calculating  the  flow  of  oil  in  pipes  are  given  by  Preston 
in  Chemical  and  Metallurgical  Engineering,  1920,  pp.  607, 
685. 

Railway  tank  cars  are  also  largely  used  for  the  transport 
of  crude  oil  and  liquid  petroleum  products.  Tank  cars 
supplied  with  steam  coils,  which  can  be  connected  up  to  a 
steam  line,  at  the  discharging  stations,  are  used  for  the 
transport  of  heavy  lubricating  oils  and  even  asphalts  which 
are  solid  at  ordinary  temperatures. 

The  design  of  such  cars  depends  to  a  large  extent  on  the 
conditions  laid  down  by  the  railway  companies  over  whose 
lines  the  cars  must  run.  Cars  designed  to  carry  benzines 
or  other  inflammable  products  are  usually  not  permitted  to 
have  any  connections  to  the  bottoms  of  the  tanks,  but  must 
be  pumped  out  by  means  of  the  manhole  or  connections  on 
the  expansion  dome  on  the  top  of  the  car. 

Transport  by  sea  is  effected  by  means  of  specially 
designed  tank  steamers,  which  are  sometimes  fitted  with 
steam-heating  coils  to  facilitate  the  discharge  of  heavy 
viscous  fuel  oils.  In  the  majority  of  tank  steamers  the 
engines  are  usually  fitted  aft,  in  order  to  avoid  the  necessity 
for  constructing  an  oil-tight  shaft  tunnel  which  must  pass 
through  the  oil  tanks,  if  the  engines  were  placed  midships. 
The  engine  space  aft,  and  the  stores,  and  crew's  accommoda- 
tion forward,  are  separated  off  from  the  oil  tanks  by  means 
of  "  coffer-dams."  These  are  made  of  two  water-tight  steel 
transverse  bulkheads,  a  few  feet  apart,  the  space  between 
these  forming  tanks  which  are  filled  with  water.  The  oil 
tanks  are  thus  isolated  fore  and  aft  from  the  rest  of  the  ship 
by  means  of  two  solid  walls  of  water.  The  ship  is  usually 
divided  into  a  number  of  tanks  by  transverse  bulkheads, 
and  each  tank  is  divided  into  a  port  and  starboard  portion 
by  means  of  a  longitudinal  bulkhead.  In  order  to  avoid 
"  slack  tanks,"  i.e.  tanks  partly  filled,  and  to  allow  for  the 
expansion  and  contraction  of  the  oil  owing  to  changes  of 
temperature,  there  are  fitted  on  to  the  top  of  the  tanks 
"  expansion  trunks  "  of  relatively  small  cross  section.  These 


STORAGE  AND   TRANSPORT  OF  CRUDE  OIL    91 

expansion  trunks  further  allow  of  more  accurate  gauging  of 
the  quantity  of  oil  in  the  tanks.  Further,  in  order  that  the 
full  carrying  capacity  of  the  ship  may  be  utilized  when 
carrying  oils  of  low  specific  gravity,  several  smaller  tanks  on 


iwiiin 


top  of  the  main  tanks,  termed  "  summer  tanks  "  are  usually 
fitted.  The  arrangement  of  the  tanks  will  be  readily  under- 
stood from  an  inspection  of  the  diagram  (Fig.  14). 

The  ship  is  fitted  with  one  or  more  pump-rooms  in 


92      PETROLEUM  AND  ALLIED  INDUSTRIES 

which  the  discharge  pumps  are  situated  as  low  down  as 
possible.  One  or  more  suction  lines  extend  through  the 
tanks,  and  are  fitted  with  valves  operated  by  spindles 
extending  to  the  upper  deck.  The  discharge  line  is  con- 
nected to  the  line  on  the  wharf  by  means  of  flexible  hoses  or 
a  jointed  steel  swing  pipe.  Modern  tank  steamers  are 
built  up  to  capacities  of  15,000  tons  and  can  discharge  this 
oil  at  the  rate  of  as  much  as  400  tons  per  hour. 

The  total  tanker  tonnage  of  the  world  now  amounts  to 
over  3,500,000  tons.  This  large  fleet  consists  of  709  steam 
or  motor  driven  vessels  and  124  sailing  ships,  and  a  further 
250  or  thereabouts  are  under  construction. 

The  evolution  of  the  modern  tank  steamer  has  been  well 
described  by  II.  Barringer  in  the  J.I.P.T.,  vol.  i,  1915, 
p.  280. 


REFERENCES   TO   PART   III.,   SECTION   C. 

Barringer,  "  Oil  Storage,"  J.I.P.T.,  vol.  2,  1916,  p.  122. 

Engler-Hofer,  "  Das  Erdol,"  vol.  5.     Hirzel,  Leipzig. 

Pogue,  "Economics  of  Petroleum."     J.  Wiley  &  Sons,  New  York. 


SECTION  P.—  THE  DEHYDRATION  OF  CRUDE 
OILS   ON  THE  FIELDS 

CRUDE  oil  as  it  issues  from  the  well  is  often  mixed  with 
water,  which  is  often  saline,  the  water  being  emulsified  in 
the  oil.  As  the  transport  of  such  water-containing  oil  by 
pipe-line  or  tank  steamer  really  involves  freight  charges  on 
the  contained  water,  steps  are  taken  to  dehydrate  such  oils 
on  the  fields  as  far  as  possible  before  transport  to  the 
refineries.  This  dehydration  may  often  be  more  or  less 
completely  effected,  especially  in  the  case  of  crudes  of  low 
specific  gravity,  by  merely  standing  in  storage  tanks.  In 
such  cases  most  of  the  water  settles  out,  sometimes  clear, 
but  often  in  the  form  of  a  thick  emulsion  (known  as  B.S.  or 
"  bottom  settlings  ")  which  can  be  drawn  off.  This  emulsion 
still  contains  considerable  proportions  of  oil,  and  may  be 
separately  treated  by  one  of  the  methods  described  below. 
Many  heavy  crudes  do  not,  however,  readily  separate  out 
the  water,  some  in  fact  retain  it  obstinately.  Such  must  be 
subjected  to  special  treatment,  as  apart  from  the  question 
of  unnecessary  transport  of  water,  the  distillation  of  emulsified 
oil  presents  difficulties. 

Several  methods  for  treating  such  heavy  emulsions  or 
watery  crude  oils  have  been  devised. 

(a)  Methods  depending  on  the  action  of  electrolytes, 
e.g.  dilute  acids,  or  solutions  of  metallic  salts,  have  been 
suggested  and  occasionally  employed.     Such  methods  have, 
however,  met  with  little  success. 

(b)  Centrifugal  Methods. — The  separation  of  emulsified 
oil  is  usually  effected  in  the  laboratory  by  an  ordinary  hand- 
driven  centrifugal  apparatus,  the  action  being  accelerated 
by  the  dilution  of  the  oil  with  benzine.     Such  a  method 

93 


94     PETROLEUM  AND  ALLIED  INDUSTRIES 

would,  however,  be  generally  too  costly  in  practice,  as  the 
benzine  would  need  to  be  separated  off  again  by  distillation. 
The  centrifugal  principle  has  recently  been  employed  with 
success  in  the  Sharpies  super-centrifugal  apparatus,  which 
is  now  in  operation  in  many  fields  for  the  treatment  of 
crudes  containing  water  in  suspension. 

The  -centrifugal  machine  employed  operates  at  a  speed 

of  17,000  revolutions  per 
minute,  exerting  a  sepa- 
rating force  nearly  17,000 
times  that  of  gravity. 
The  machine  consists  of 
a  rotor,  a  cylindrical 
vessel  36  inches  long  and 
4 1  inches  diameter,  sus- 
pended in  a  vertical 
position  from  a  spindle 
rotating  in  a  ball  bearing. 
The  rotor  or  bowl  (Fig. 
15)  is  a  plain  cylindrical 
tube  provided  with  an 
inlet  port  at  the  lower  end 
and  outlet  ports  at  the 
upper  end,  through  the 
outer  of  which  water  runs 
off,  and  through  the  inner, 
oil.  The  machine  thus 
functions  as  a  separating 
tank  acting  under  an  enor- 

FIG.  15.— Sharpies  super-centrifugal       mOusly  increased  gravita- 
machme.  J 

tional  force. 

The  oil  to  be  dehydrated  is  fed  in  at  the  bottom  and 
under  the  influence  of  the  centrifugal  force  separates  into 
two  layers,  the  outer  (G)  being  water  with  little  or  no  oil, 
the  inner  (H)  being  oil  with  little  or  no  water.  The  water 
flows  off  through  the  lower  port  (J),  the  oil  through  the 
inner  port  (D),  these  being  collected  separately  in  the 
receivers  K  and  I 


DEHYDRATION  OF  CRUDE  OILS   ON  FIELDS    95 

The  rate  of  flow  through  the  apparatus  is  controlled  by 
the  rate  of  feed,  this  being  adjusted  so  as  to  permit  the  oil 
to  remain  in  the  apparatus  sufficiently  long  to  allow  of 
separation  of  the  water  taking  place. 

The  capacity  of  a  machine  of  the  dimensions  given  above 
will  naturally  depend  on  the  nature  of  the  emulsion  under 
treatment,  but  it  may  be  taken  that  an  emulsion  containing 
8  per  cent,  of  water  could  be  handled  at  the  rate  of  about 
ij  tons  per  hour.  The  apparatus  can  also  be  used  to  effect 
a  separation  of  oil  from  the  sludge  which  settles  out  on  the 
bottoms  of  storage  tanks,  a  product  which  is  otherwise 
difficult  to  handle  (U.S.  Pat.  No.  1232104). 

(c)  Electric  Methods. — It  has  been  found  that  crude 
oil  emulsions  readily  separate  out  into  their  constituents 
when  placed  in  a  strong  static  electric  field.     This  principle 
has  been  employed  in  various  processes  which  are  now  in 
common  use  for  treating  watery  crudes. 

A  usual  type  of  plant  consists  of  a  tank,  eight  or  nine 
feet  diameter  and  about  double  that  in  height,  fitted  with 
water  draw-off  and  heating  coils.  The  body  of  the  tank  is 
filled  with  a  series  of  flat  parallel  plates,  alternate  members 
of  which  are  earthed  to  the  tank,  the  others  being  connected 
up  to  a  transformer  which  supplies  single  phase  alternating 
current  at  11,000  volts. 

The  emulsified  crude  oil  is  pumped  in  near  the  bottom 
of  the  tank,  the  water  separates  out  and  is  drawn  off,  and 
the  emulsion-free  oil  passes  off  from  the  top.  In  another 
well-known  type  of  plant  (the  Cottrell)  one  electrode  consists 
of  a  central  revolving  cage  built  up  of  a  central  axis  carrying 
metallic  discs,  the  other  electrode  being  the  outer  wall  of  the 
cylindrical  tank.  The  actual  way  in  which  the  separation 
of  the  emulsion  in  such  plants  takes  place  is  not  fully  under- 
stood. 

Oil  containing  85  per  cent,  of  water  has  been  in  this  way 
successfully  treated.  The  cost  of  operation  is  very  low  and 
the  plant  requires  very  little  attention.  (Electrical  Review, 
New  York,  October  25,  1919.) 

(d)  Heating  under  Pressure.— Most  crude  oil  emulsions 


96      PETROLEUM  AND  ALLIED  INDUSTRIES 

may  be  separated  effectively  by  heating  under  pressure. 
Pressure  is  necessary  as  the  splitting  point  is  usually  above 
the  boiling  point  of  water  at  ordinary  pressure.  This 
method,  which  works  well  in  the  laboratory,  has  not,  however, 
so  far  been  applied  in  practice. 

(e)  Distillation  Methods. — The  distillation  of  wet  crude 
oil  in  ordinary  stills  presents  technical  difficulties  owing  to 
the  liability  to  boil  over  or  "  puke."  This  difficulty  is  got 
over  by  distillation  in  tubular  retorts,  the  foaming  mass  of 
hot  oil,  steam,  and  vapours  being  allowed  to  pass  into  a 
large  vessel,  a  separating  box,  whence  the  steam  and  vapours 
pass  off  to  condensers,  the  dehydrated  crude  running  out 
from  the  bottom  through  heat  exchangers  to  storage.  Such 
dehydrating  plants  are  now  common,  and  are  often  used  to 
distil  off  some  of  the  volatile  fractions  from  a  crude  oil  as 
well  as  the  water.  They  are  consequently  often  termed 
"  topping  "  or  "  skimming  "  plants.  They  are  described  in 
detail  under  distillation  plant  (vide  Part  VII.,  Sect.  A),  to 
which  the  reader  is  referred. 


GENERAL    REFERENCES    TO    PART   III.,    SECTION    D. 

Sherrick,  "Oil  Field  Emulsions."      /.  Ind.  and  En°.  Chem.,  Feb.  1920. 
Thomas,  "Review  of  the  Literature  of  Emulsions,"  /.  Ind.  and  Eng. 
Chem.,  Feb.  1920. 


PART  IV.— CRUDE  OILS  PRODUCED  BY 
THE  DISTILLATION  OF  SHALES, 
COALS,  LIGNITES,  AND  THE  LIKE 

SECTION  A.— CHARACTERS  AND  DISTRIBU- 
TION OF   OIL  SHALE 

THE  shale  oil  and  petroleum  industries,  though  of  about 
the  same  age,  have  developed  to  very  different  extents, 
the  former  being  at  the  present  tune  of  relatively  little 
importance.  Shale  oils  have  so  far  always  been  in  the 
unfortunate  position  of  having  to  face  the  competition  of 
the  more  cheaply  manufactured  products  of  petroleum, 
in  consequence  of  which  the  shale-oil  industry  has  had  a 
somewhat  checkered  career.  It  owes  its  continued  existence 
indeed  largely  to  the  fact  that  ammonium  sulphate  is 
produced  as  a  by-product. 

There  can  be  no  doubt,  however,  that  a  great  future 
is  in  store  for  this  industry,  the  development  of  which  will 
become  of  increasingly  greater  importance  as  the  demand  for 
petroleum  products  increases.  Immense  though  the 
potentialities  of  petroleum  production  are,  the  end  of 
many  important  oil-fields  is  in  sight.  In  the  United  States, 
for  example,  where  enormous  deposits  of  oil  shale  exist, 
the  importance  of  the  development  of  this  industry  is  fully 
realized  and  active  efforts  are  being  made  to  establish  it 
on  a  firm  basis. 

Oil  shales  as  distinct  from  oil  sands  do  not  normally 
contain  oil  as  such,  as  they  yield  up  little  or  no  portion  of 
their  organic  content  to  solvents.  The  oil  obtained  from 
oil  shales  is  produced  as  a  result  of  the  chemical  changes 
brought  about  by  the  action  of  heat.  Oil  sands,  on  the 
contrary,  readily  yield  up  their  bituminous  material  to  such 
p.  97  7 


g8      PETROLEUM  AND  ALLIED  INDUSTRIES 

solvents  as  carbon  disulphide.  There  are,  however,  certain 
types  of  shale  which  do  yield  an  appreciable  content  of 
soluble  material.  J.  Gavin,  in  a  report  recently  issued 
by  the  U.S.  Bureau  of  Mines,  entitled  "  The  Solubility  of 
Oil  Shales  in  Solvents  for  Petroleum,"  has  investigated  this 
subject.  He  finds  that  in  the  case  of  a  Colorado  shale 
2*04  per  cent,  in  carbon  tetrachloride,  1*85  per  cent,  in 
carbon  bisulphide,  133  per  cent,  in  acetone,  2*23  per  cent, 
in  benzol,  and  2*41  per  cent,  in  chloroform,  these  figures 
representing  from  10  to  18  per  cent,  of  the  yield  of  oil  obtain- 
able by  distillation.  He  points  out,  however,  that  the 
extracted  material  is  not  oil,  in  the  common  sense  of  the 
word,  but  resembles  certain  of  the  natural  products  which 
are  supposed  to  have  resulted  from  oxidation  of  petroleum. 
He  also  points  out  that  the  solubility  of  an  oil  shale  is  not 
an  index  of  its  relative  oil  yield. 

Oil  shales  are  often  termed  bituminous  shales,  just  as 
types  of  coal  are  described  as  bituminous.  The  author 
does  not  like  the  use  of  the  term  "  bituminous  "  in  this 
connection  as  the  shales  really  contain  no  bitumen  as  such. 
Pyrobituminous  shales  is  a  more  accurate  term ;  however, 
to  avoid  any  misunderstanding  the  term  "  oil  shale  "  may  be 
used.  A  shale  saturated  with  petroleum  would  be  termed 
a  "petroliferous"  shale. 

Oil  shales  are  thus  composed  of  two  classes  of  constituents, 
the  inorganic  material  which  remains  as  ash  after  distillation, 
and  the  organic  material,  the  thermal  decomposition  of 
which  gives  rise  to  the  crude  oil.  The  organic  material  of 
shales  is  usually  designated  by  the  term  "  kerogen." 

Oil  shales  show  great  variation  in  properties,  not  only 
of  the  inorganic,  but  also  of  the  organic  components.  In 
general  they  are  stratified  rocks  composed  largely  of 
argillaceous,  though  sometimes  of  calcareous  material. 
They  are  usually  dark  in  colour,  but  sometimes  brownish 
or  even  yellowish,  sometimes  hard  and  brittle,  but  often 
tough  and  capable  of  being  cut  with  a  knife.  They  occur 
in  beds  ranging  from  a  few  inches  in  thickness  to  many  feet. 
In  many  cases  the  total  thickness  of  the  shale  beds  in  one 


CHARACTERS   OF  OIL  SHALES  99 

shale-bearing  formation  amounts  to  many  hundreds  of 
feet. 

The  inorganic  portion  of  a  shale  may  be  considered  merely 
as  a  carrier  for  the  organic  material.  The  organic  portion, 
the  so-called  "  kerogen,"  shows  great  differences  of  character 
in  different  shales. 

This  great  variation  in  character  is  illustrated  by  the 
following  ultimate  analyses  of  the  organic  part  of  various 
shales  from  different  sources  : — 

1  ..  .v.  76-9  8'8  4-4  27  7*i 

2  . .  . .  70-8  9-6  14-5  2*3  2*8 

3  ..  ..  69-6  8'i  20*3  0-2  1-8 

4  . .  . .  68*4  8'6  4*9  0*9  17-2 

5  ••         •-        66'8         9*3         J77         * '&          4*4 

6  ..         ..        64-1         6*8         23*6         2*i  3*4 

7  ..         ..        58-6         8*0         22*4         i'i  9*9 

The  ratio  carbon/hydrogen  varies  from  7*2  to  9*4.  The 
extreme  variations  in  oxygen  and  sulphur  content  are  very 
noticeable.  The  above  analyses  were  made  on  individual 
shales  from  various  countries.  Individual  samples  from 
various  seams  in  the  same  area  even  display  considerable 
variation  in  character. 

Considerable  attention  has  been  given  by  Cunningham- 
Craig  to  the  microscopic  study  of  oil  shales,  torbanites,  and 
cannel  coals  (J.I.P.T.,  vol.  2,  p.  238).  He  points  out  that  a 
distinct  substance  varying  in  colour  from  a  pale  yellow  to  a 
deep  reddish-brown  as  viewed  in  a  microscopic  section,  is 
characteristic  of  all  oil  shales  and  cannel  coals.  This  peculiar 
yellow  body  shows  no  definite  structure,  and  under  the 
microscope  shows  irregular  shapes  often  completely 
imbedding  portions  of  the  mineral  matter.  As  a  result 
of  a  considerable  amount  of  microscopic  research,  Craig 
has  come  to  the  conclusion  that  in  the  case  of  boghead 
coals,  or  torbanites,  this  "  kerogen "  has  developed  in 
situ,  but  that  in  oil  shales  it  may  have  been  largely  introduced 
from  some  outside  source. 


ioo    PETROLEUM   AND  ALLIED  INDUSTRIES 


Of  the  chemical  nature  of  this  "  kerogen  "  little  definite 
is  at  present  known,  but  there  is  evidence  which  points  to 
its  being  derived,  at  least  in  the  case  of  certain  oil  shales, 
from  crude  petroleum.  It  has  not  yet  been  isolated,  as  it 
is  practically  insoluble  in  any  of  the  known  solvents.  In 
this  respect  it  bears  some  resemblance  to  the  naturally 
occurring  kerites  (usually  termed  "asphaltites"),  wurzilite, 
and  albertite.  This  resemblance  is  further  borne  out  by 
the  fact  that  the  carbon/hydrogen  ratio  is  of  the  same  order, 
7  to  i,  being  markedly  different  from  that  characteristic  of 
bituminous  coal,  15  to  i,  but  not  so  different  from  that  of 
cannel  coal,  10*5  to  i. 

Some  light  on  the  probable  origin  of  this  kerogen  has 
been  thrown  by  the  recent  researches  of  Hackford  (Trans. 
Am.  Inst.  of  Mining  and  Metallurgical  Engineers,  1920).  He 
found  that  by  treating  a  Pennsylvania  lubricating  oil  with 
oxygen  or  sulphur  at  a  temperature  of  only  100°  C.  practically 
the  whole,  after  a  long  period,  gradually  changed  into  bodies 
practically  insoluble  in  any  of  the  known  solvents.  These 
substances  he  termed  kerotenes,  and  he  found  them  to  bear 
a  great  resemblance  to  the  kerogen  of  shales.  Naturally 
occurring  bodies,  intermediate  in  character  between  petroleum 
and  these  kerotenes,  are  indeed  known,  the  asphaltites  and 
glance  pitches.  The  following  table  illustrates  this  point  : — 


Substance. 

Per  cent,  sol- 
uble in  carbon 
bisulphide. 

Per  cent,  sol- 
uble in  petro- 
leum spirit. 
Sp.gr.  0-645. 

Per  cent, 
fixed  carbon. 

Asphaltmade  from  Mexican  petroleum 
Gilsonite 

99'9 
about  98 

60 

40  to  60 

12 

10  to  20 

Barbados  Manjak 

about  98 

25  to  30 

25  to  30 

Grahamite 

.  . 

about  99 

about  i 

45  to  55 

Albertite 

slightly 

trace 

about  55 

The  work  of  Hackford  indicates  that  these  bodies  repre- 
sent steps  in  a  process  of  gradual  change  which  petroleum 
may  undergo,  the  final  result  of  which  is  the  kerotenes, 
which  are  certainly  very  similar  to,  if  not  identical  with,  the 
kerogen  of  some  pyrobituminous  shales. 


CHARACTERS  OF  OIL   SHALES  101 

On  this  view,  then,  an  oil  shale  would  appear  to  be  the 
result  of  such  a  change  having  taken  place  in  a  rock  which 
had  been  saturated  with  crude  petroleum.  This  gradual 
transformation  has  been  termed  "  inspissation."  Evidences 
that  this  is  actually  going  on  in  nature  are  not  wanting. 
Oil  sands  more  or  less  weathered  and  oil  from  seepages, 
and  intruded  asphalts  have  been  shown  to  contain  propor- 
tions of  insoluble  kerotenes  up  to  as  much  as  30  per  cent. 

The  well-known  albertite  vein  of  New  Brunswick  is 
connected  with  a  bituminous  sandstone  which  still  contains 
oil.  There  can  be  little  doubt  that  this  albertite,  which  so 
nearly  resembles  coal  in  some  respects,  is  a  highly  inspissated 
petroleum  product.  The  rocks  which  this  vein  traverses 
have  actually  been  converted  into  true  kerogen-containing 
oil  shales. 

This  process  of  inspissation  seems  further  to  bring  about 
a  concentration  of  the  sulphur  and  nitrogen  found  in  the 
original  crude  oil.  For  example,  many  crude  petroleums 
contain  less  than  i  per  cent,  of  sulphur,  the  heavy  asphaltic 
oils  of  Mexico  5  per  cent.,  the  thiokerite  wurzilite  5*8  per 
cent.,  and  a  similar  thiokerite  from  Nova  Zembla  as  much 
as  15  per  cent.  (Hackford.  loc.  cit.).  Ohio  crude  oil  contains 
0'2  per  cent,  of  nitrogen,  some  Calif ornian  oils  175,  and 
albertite  175  per  cent.  The  relatively  high  nitrogen  and 
sulphur  content  of  shales  perhaps  also  lends  support  to  the 
view  that  oil  shales  are  merely  shales  (or  other  types  of 
rock)  which  were  once  impregnated  with  crude  oil,  which 
has  slowly  undergone  inspissation  in  the  manner  suggested 
above.  As  Craig  says,  "  an  oil-shale  field  may  be  considered 
as  the  relics  of  a  former  oil-field." 

Conacher,  on  the  other  hand  (Geol.  Soc.,  Glasgow,  1916,  p. 
164),  considers  that  the  organic  matter  in  the  shale  is  of  vege- 
table origin,  partly  resinous  in  character.  As  the  solubility 
of  resins  decreases  with  age,  the  failure  of  solvents  to  extract 
the  organic  matter  from  shales  does  not  disprove  this  theory. 

Hngler  (Petroleum,  vol.  7,  p.  399)  considers  that  the  pyro- 
bitumens  of  shales  are  of  vegetable  origin,  formed  perhaps 
with  such  bodies  as  montan  wax,  as  intermediate  products. 


102    PETROLEUM  AND  ALLIED  INDUSTRIES 


It  is  interesting  to  note  in  this  connection  that  Jones 
and  Wheeler  (J.C.S.,  1916,  p.  767)  state  that  coal  can  be 
resolved  into  cellulosic  and  resinic  parts,  the  former  of 
which  on  distillation  yields  phenolic  bodies,  the  latter 
hydrocarbons. 

Oil  shales  differ  greatly  in  character.  It  is  highly 
improbable  that  shales  so  diverse  in  character  should  have 
similar  origins.  Some  would  appear  to  be  derived  from 
petroleum,  others  directly  from  organic  matter.  As  in  the 
case  of  crude  petroleums,  the  question  of  their  origin  is  at 
present  far  from  being  decided. 

For  comparative  purposes  a  few  shale  analyses  are 
appended  : — 


Locality. 

Sp.gr.  of 
shale. 

Volatile 
matter. 

Fixed 
carbon. 

Ash. 

Sulphur. 

Scotland  — 

o/ 
/o 

o/ 
/o 

o/ 
/o 

o/ 
/o 

i.  Torbanite 

I-27 

61-42 

8-81 

29-17 

0-277 

2.  Cobbinshaw 

1-62 

37-16 

8-24 

53-64 

1-435 

3.  Tarbrax 

1-81 

30-86 

8-82 

5871 

3-053 

4.  Newliston 

1-81 

27-38 

8-78 

62-27 

I'lIO 

5.  Hayscraigs 

2-05 

22-43 

5-15 

70-70 

Q-622 

6.  Deans 

2-23 

15-28 

4^3 

77*7 

0-528 

Kimmeridge 

39'i 

n-8 

46-6 

— 

tl 

— 

22-7 

11-7 

65-6 

— 

Norfolk 

I  '3 

35'i 

I5-3 

39'8 

— 

,, 

—  . 

32-9 

9-0 

55-o 

4-0 

Colorado 

i  '95 

37'5 

5'° 

56-8 

I  '2 

Locality. 

Imperial  gallons 
per  ton. 

Lbs.  ammonium 
sulphate  per  ton. 

Albert,  N.B. 

35 

47 

Argentina,  Rio  Grande 

So 

California,  Kern  Co. 

52 

— 

Santa  Maria 

32 

— 

Esthonia 

1  60 

, 

France,  Autun 

18 

27 

Kentucky 

23 

98 

New  South  Wales,  Newne 

80 

— 

New  Zealand,  Waikaia 

38 

19 

Picton,  Nova  Scotia 

14 

41 

Queensland,  Narrows 

28 

47 

Scotland,  Broxburn 

37 

12 

Fells 

26-40 

20-35 

,,        Raeburn 

54 

7 

Tasmania,  Mersey 

40 

Transvaal 

28 



Utah 

40 

17 

DISTRIBUTION  OF  OIL  SHALES  103 

As  the  variation  in  character,  even  of  different  seams  in 
the  same  group,  is  so  great,  generalizations  about  the  cha- 
racters of  various  shales  in  various  localities  cannot  be  drawn 
with  any  degree  of  accuracy. 

A  scientific  classification  of  shales  is  hardly  yet  possible. 
They  may,  however,  be  roughly  grouped  into  asphaltic 
pyrobituminous  shales,  i.e.  those  of  which  the  organic 
matter  contains  little  or  no  oxygen,  such  as  those  of  New 
Brunswick  and  Nova  Scotia,  and  non-asphaltic  pyrobitu- 
minous shales,  i.e.  those  of  which  the  organic  matter  does 
contain  oxygen.  This  class  includes  cannel  coals,  torbanites, 
and  many  oil  shales  (McKee  and  Lyder,  /.  Ind.  and  Eng. 
Chem.,  1921,  p.  613). 

Oil  shales  are  widely  distributed  and  found  in  many  parts 
of  the  world  where  oil  has  not  yet  been  proved  to  exist. 

In  the  British  Isles  shales  are  found  in  Scotland,  in  the 
Lothians  on  the  south  side  of  the  Firth  of  Forth,  where  a 
thriving  industry  has  now  been  established  for  more  than 
half  a  century.  The  shales  here  occur  in  the  calciferous 
sandstone  series,  the  lowest  division  of  the  Carboniferous 
system  (Cadell  and  Wilson,  "  The  Oil  Shales  of  the  Lothians," 
Memoirs  Geological  Survey,  Scotland) . 

The  Torbane  Hill  shale,  which  was  extensively  worked 
there,  at  one  time  yielded  from  80  to  130  gallons  of  crude  oil 
per  ton.  This  material  has  now,  however,  been  completely 
exhausted.  The  shales  now  worked  yield  on  the  average 
not  more  than  20  to  30  gallons  of  crude  oil  per  ton,  but  yield 
also  about  60  Ibs.  of  ammonium  sulphate  to  the  ton.  The 
shales  from  individual  seams  show  great  variation,  some  of 
those  worked  yielding  only  16  gallons  of  oil  to  the  ton,  others 
as  much  as  50. 

Extensive  oil-shale  deposits  are  now  being  developed  in 
Norfolk,  England  (Forbes-Leslie,  J.I.P.T.,  1916,  p.  3). 
The  dip  of  the  strata  here  is  very  gentle  and  the  covering 
surface  deposits  are  thin,  so  that  the  shale  can  be  quarried 
from  the  surface.  These  shales  are  richer  than  those 
of  Scotland,  and  it  is  claimed  that  the  crude  oils  resulting 
from  the  distillation  are  of  good  quality  and  can  be  easily 


104    PETROLEUM  AND  ALLIED  INDUSTRIES 

refined  in  spite  of  their  high  sulphur  content.  The  industry 
in  Norfolk,  however,  is  in  its  infancy,  so  developments  will 
be  awaited  with  great  interest.  These  shales  are  of  the  same 
age  as  those  which  are  found  in  Dorsetshire  in  the  Kimmeridge 
Clay.  These  latter  shales  were  actually  worked  as  far  back 
as  1848,  and  for  the  following  twenty  years  or  so  various 
companies  attempted  to  carry  on  the  industry  but  in  every 
case  without  success.  The  crude  oil  from  Kimmeridge 
shale  is  very  rich  in  sulphur  compounds  (the  crude  oil 
containing  about  8  per  cent,  of  sulphur),  and  as  these  com- 
pounds are  as  stable  as  the  hydrocarbons  themselves,  no 
methods  of  successfully  refining  this  oil  have  yet  been  evolved 
(Mansfield,  J.I.P.T.,  vol.  2,  p.  162). 

The  shale-oil  industry  in  France  dates  back  to  1830. 
The  deposits  at  Autun  and  at  Broxiere  I^es  Mines  have  an 
annual  output  of  about  750,000  tons  of  shale.  These 
shales  yield  about  50  gallons  of  oil  to  the  ton.  Richer 
shales,  yielding  80  to  120  gallons  per  ton,  are  also  worked 
in  the  Riviera  (Petroleum  Times,  September  20,  1919). 
Oil  shales  occur  also  in  Wurtemburg,  Spain,  Sweden, 
Italy,  Bulgaria,  Turkey,  and  Austria  (Journal  Royal 
Society  of  Arts,  December  24,  1920),  but  none  of  these 
deposits  have  yet  been  commercially  exploited.  In  Canada 
vast  deposits  are  found. 

The  rich  shales  of  Esthonia  have  recently  given  rise  to 
an  industry.  They  are  used  for  (i)  distilling  to  obtain  oils, 
(2)  for  gas  making,  (3)  mixed  with  pulverized  coal  for 
cement  burning,  (4)  as  fuel  in  place  of  coal.  These  shales 
are  very  rich,  yielding  29  per  cent,  of  oil,  i.e.  about  75  gallons 
to  the  ton  (Shale  Rev.,  1921,  Nos.  4,  5). 

In  Canada  vast  deposits  are  found  in  Northern  Saskat- 
chewan.  In  New  Brunswick  oil  shales  are  found  in  three 
areas.  These  yield  from  27  to  57  gallons  per  ton  of  crude 
oil,  varying  in  specific  gravity  from  0-890  to  0-925,  and 
ammonium  sulphate  in  quantities  varying  from  30  to  no  Ibs. 
per  ton.  These  shales  are  now  being  exploited  (R.  Ells, 
"The  Bituminous  Shales  of  New  Brunswick  and  Nova 
Scotia,"  Canada  Dept.  of  Mines,  1910).  The  oil  shales  of 


DISTRIBUTION  OF  OIL  SHALES  105 

Nova  Scotia  are  relatively  poor  in  respect  to  both  oil  and 
ammonium  sulphate.  Those  of  Newfoundland  cover  a 
large  area  and  yield  about  50  gallons  crude  oil  and  80  Ibs. 
ammonium  sulphate  per  ton.  Deposits  of  similar  character 
are  found  in  the  province  of  Quebec. 

In  the  United  States,  vast  deposits  of  oil  shale  occur, 
those  of  Colorado  alone  covering  an  area  of  2500 
square  miles,  being  estimated  to  be  capable  of  supplying 
8,000,000,000  tons  of  crude  oil.  In  Utah  more  than 
40,000,000,000  tons  of  shale  capable  of  yielding  35  gallons 
to  the  ton  are  available.  Those  of  Kentucky  yield  22 
gallons  of  oil  and  97  Ibs.  of  ammonium  sulphate  per  ton. 
Wyoming,  Texas,  Montana,  and  West  Virginia  possess 
extensive  deposits,  as  do  also  California,  Kansas, 
Oklahoma,  Nevada,  and  New  Mexico. 

Vigorous  efforts  are  now  being  made  in  the  United  States 
to  set  the  oil-shale  industry  on  a  sound  economic  footing. 

Shales  in  the  Transvaal  have  yielded  from  30  to  90 
gallons  of  crude  oil  to  the  ton,  but  the  beds  are  usually  thin 
and  therefore  expensive  to  work  (T.  G.  Trevor,  "An  Oil- 
Shale  Industry  for  South  Africa,"  South  African  Journal 
of  Industries,  August,  1920). 

There  are  indications  too  of  extensive  deposits  in  Brazil 
and  in  China. 

Extensive  deposits  of  rich  oil  shales  are  found  in  the 
Wolgan  Valley  area  in  New  South  Wales.  These  have  been 
worked  for  some  years,  but  so  far  with  disappointing  results. 
In  New  Zealand  and  Tasmania  oil  shales  are  also  known. 
These  latter  deposits  have  been  estimated  at  5,000,000 
tons  and  are  now  in  process  of  development. 

GENERAL   REFERENCES   TO   PART   IV.,   SECTION   A. 

Alderson,  "  The  Oil-Shale  Industry."     F.  A.  Stokes  Co.,  New  York. 

Baskerville,  "  American  Oil  Shales."  /.  Ind.  and  Eng.  Chem.,  vol.  5, 
1913,  p.  73. 

Cronshaw,  "  Oil  Shales."  Imperial  Institute  Monograph.  J.  Murray, 
1921. 

Greene,  "  A  Treatise  on  British  Mineral  Oil."     Griffin  and  Co. 

Quarterly  Journal  of  the  Colorado  School  of  Mines. 

Scheithauer,  "  Shale  Oils  and  Tars."     Scott,  Greenwood  and  Co. 


SECTION  B.— THE  MINING  OF  SHALES 

THE  shale-oil  industry,  in  contrast  to  the  petroleum  industry 
proper,  must  always  be  severely  handicapped  by  the  fact 
that  the  crude  shale  oil,  the  real  starting  point  for  the  manu- 
facture of  the  oil  products,  must  in  every  case  be  manu- 
factured. The  factor  of  the  cost  of  mining  the  shale  becomes, 
therefore,  one  of  supreme  importance,  the  more  particularly 
so  as  the  percentage  of  oil  derived  from  the  shale  is  often 
less  than  twenty.  The  cost  of  mining  the  shale,  therefore, 
will  often  be  the  factor  which  determines  the  chance  of 
success  of  any  shale  proposition. 

The  method  of  mining  to  be  adopted  in  any  locality 
will  depend  upon  various  factors,  such  as  the  depth  at  which 
the  shale  strata  are  found ;  their  dip  or  inclination  to  the 
horizontal ;  the  thickness  of  the  shale  seams,  and  the 
nature  of  the  overlying  beds. 

The  methods  employed  may  be  divided  into  two  groups  : 

(a)  The  open  cut  or  quarrying  method. 

(b)  The  mining  methods. 

In  many  localities,  such  as  Grand  Valley,  Colorado, 
the  shale  forms  prominent  hills,  so  that  the  shale  can  be 
quarried  by  ordinary  methods  and  transported  by  gravity 
conveyors  to  the  shale  retorting  plant  at  lower  levels,  this 
being  the  cheapest  method  of  working.  In  other  areas, 
such  as  Norfolk,  the  shale  beds  lie  close  to  the  surface  with  a 
gentle  dip.  Under  these  conditions  steam  shovels  may  be 
used.  In  any  case,  however,  a  considerable  quantity  of 
surface  material  must  be  removed.  The  cost  of  such 
operations  is  low,  being  only  three  or  four  shillings  per  ton. 

In  some  cases,  the  shales  may  be  worked  by  horizontal 

1 06 


THE  MINING  OF  SHALES       107 

adits  driven  into  the  side  of  a  hill,  as  is  the  case  in  Wolgan 
Valley,  New  South  Wales. 

In  many  cases,  however,  the  shales  may  be  at  greater 
depths,  the  strata  being  either  inclined  or  more  or  less 
horizontal.  In  such  cases  ordinary  mining  methods  must 
be  adopted.  A  vertical  shaft  may  be  sunk  from  which  the 
level  crosscuts  may  be  driven  ;  or  an  inclined  shaft  may  be 
sunk  along  one  of  the  beds  of  shale,  from  which  the  crosscuts 
branch  off. 

The  oil  shales  of  Scotland  are  worked  in  this  manner. 
After  the  mine  has  been  driven,  the  shale  is  worked  either 
by  (i)  the  Stoop  and  Room  method,  or  (2)  the  lyong  Wall 
method.  A  detailed  description  of  the  methods  used  is, 
however,  beyond  the  scope  of  this  work.  For  such  details 
reference  may  be  made  to  "  The  Oil  Shales  of  the  I^othians," 
Part  II.,  by  W.  Caldwell,  Memoir  of  Geological  Survey  of 
Scotland,  1906. 

The  work  of  mining  shale  is  generally  simpler  than  that 
of  coal,  as  gas  is  absent.  Moreover,  grading  is  unnecessary 
as  all  the  shale  from  the  seam  being  worked  goes  to  the 
retorts  after  being  broken  up  to  suitable  size  in  the  crushers. 


SECTION  C.—  LABORATORY  EXAMINATION 
OF   OIL  SHALES 

As  the  actual  yield  of  products  obtained  on  retorting  will 
naturally  depend  to  a  considerable  extent  on  the  method  of 
retorting  employed,  it  is  difficult  or  impossible  to  devise  a 
laboratory  method  of  testing  shales  which  will  always  give 
results  comparable  with  those  obtained  in  practice.  Never- 
theless, some  method  of  testing  on  the  laboratory  scale  is 
necessary,  and  highly  useful,  both  for  exploratory  work  and 
for  the  control  of  operations  on  the  large  scale. 

Moreover,  if  the  relation  between  the  laboratory  results 
and  those  obtained  from  large-scale  operations  has  been 
worked  out  in  one  case,  other  laboratory  results  may  be 
interpreted  in  the  same  way  with  the  reservation,  of  course, 
that  such  interpretation  is  not  rigid. 

Elementary  analyses  giving  the  nitrogen,  carbon,  and 
hydrogen  content  can  be  easily  carried  out  by  the  well- 
established  methods.  Determinations  of  ash  and  volatile 
matter  are  also  easily  made.  Great  care  must,  however, 
be  exercised  in  deducing  conclusions  from  such  elementary 
analyses.  The  nitrogen  content  alone  cannot  indicate  the 
quantity  of  ammonium  sulphate  obtainable,  because  the 
whole  of  the  nitrogen  cannot  be  converted  into  ammonia. 

Many  shales  contain  in  their  mineral  matter  appreciable 
and  often  considerable  amounts  of  carbonates,  and  also 
combined  moisture,  the  latter  and  the  carbon  dioxide  in 
the  carbonates  being  evolved  on  ignition.  The  apparent 
"  volatile  matter  "  derived  from  the  organic  matter  is  thereby 
often  materially  increased,  and  in  the  elementary  analysis, 
the  percentages  of  carbon,  hydrogen,  and  oxygen  in  the 
organic  substance  are  also  exaggerated.  Hence,  in  the 

108 


LABORATORY  EXAMINATION  OF  OIL  SHALES  109 

majority  of  cases  few  deductions  of  value  can  be  made  from 
either  the  elementary  analysis  or  from  the  determination 
of  volatile  matter,  so  without  additional  information  the 
results  of  such  analyses  may  be  very  misleading. 

The  United  States  Bureau  of  Mines  has  for  the  present 
adopted  the  method  of  laboratory  testing  of  shales,  as 
worked  out  by  Bailey,  and  applied  to  the  control  of  shale 
retorting  in  Scotland.  Full  details  of  the  method  are 
published  in  "  Notes  on  the  Oil-Shale  Industry  "  by  Gavin, 
Hill,  and  Perdew,  Bureau  of  Mines,  Washington,  1919, 
from  which  the  following  description  is  abstracted  :— 

A  malleable  iron  tube  6  feet  long  and  2  inches  in  diameter, 
welded  up  at  one  end,  is  used  as  the  retort.  About  15  inches 
of  the  tube  is  partly  filled  with  shale  crushed  to  pieces  of 
the  size  of  peas.  The  tube  is  placed  with  about  18  inches 
of  its  length  (which  contains  the  shale)  in  a  furnace,  the 
other  4 1  feet  projecting  outside  the  furnace  inclined  down- 
wards towards  the  open  end,  and  acting  as  a  condenser. 

The  tube  is  gradually  heated  by  flue  gases  during  six 
hours,  being  finally  heated  to  a  bright  red.  The  portion  of 
the  tube  projecting  outside  the  furnace  is  then  gradually 
warmed  so  as  to  melt  any  oil  which  might  have  solidified 
therein,  and  to  enable  it  to  run  down  into  the  collecting  vessel 
placed  below  the  end  of  the  tube.  The  oil  must  be  separated 
from  the  water  which  comes  over  with  it,  or  the  water  in 
the  mixture  must  be  estimated  by  one  of  the  standard 
methods,  e.g.  by  distillation  with  xylene. 

The  yield  of  ammonium  sulphate  is  estimated  in  a 
similar  fashion.  A  i-inch  tube  of  malleable  iron  about 
28  inches  long  is  used.  One  end  is  connected  to  a  steam 
supply,  the  other  to  a  wash  bottle  or  tower  containing  dilute 
sulphuric  acid  (2N),  an  empty  flask  to  act  as  receiver  being 
placed  between  the  end  of  the  iron  tube  and  the  sulphuric 
acid  container.  About  30  grams  of  the  shale  are  placed 
in  the  centre  of  this  tube,  which  is  heated  to  bright  redness 
in  an  ordinary  combustion  tube.  After  5  or  6  minutes'  gentle 
heating,  when  vapours  begin  to  appear  in  the  flask,  steam  is 
allowed  to  pass  through  the  retort  at  such  a  rate  that  after 


no    PETROLEUM  AND  ALLIED  INDUSTRIES 

about  ij  hours'  heating  to  bright  redness  about  600  c.c.  of 
liquid  has  collected  in  the  flask.  The  contents  of  the  flask 
and  sulphuric  acid  absorber  are  then  filtered  and  washed 
into  a  litre  flask  and  made  up  to  a  litre,  so  that  three  succes- 
sive portions  can  be  removed  for  estimation.  This  may  be 
done  by  concentrating  by  evaporation,  the  nitrogen  in  the 
concentrate  being  estimated  by  the  nitrometer. 

The  United  States  Geological  Survey  (Bulletin  No.  641, 
p.  148)  have  standardized  a  simple  apparatus  for  field 
work.  It  consists  merely  of  a  small  iron  retort  of  about  a 
half-pint  capacity  fitted  with  closely  fitting  iron  lid  with 
clamps,  which  can  be  heated  by  a  kerosene  burner,  and  which 
is  connected  to  a  small  metal  I^iebig  condenser.  The 
condenser  is  connected  to  a  flask  with  a  two-holed  cork,  one 
of  which  takes  the  end  of  the  condenser,  the  other  a  glass 
tube  to  lead  the  permanent  gases  to  an  ammonia  scrubber. 
A  well-mixed  sample  weighing  8J  oz.  is  taken,  ground  so  as 
to  pass  through  a  J-in.  sieve.  The  number  of  cubic  centi- 
metres of  oil  obtained  is  equal  to  the  yield  of  oil  in  U.S.  gallons 
per  ton' of  shale,  provided  that  8J  oz.  of  shale  be  taken  for 
the  experiment. 

The  percentage  of  nitrogen  given  by  the  elementary 
analysis  multiplied  by  94  gives  the  approximate  yield  of 
ammonium  sulphate  in  Ibs.  per  ton  which  may  be  expected. 
It  must  be  remembered,  however,  that  the  yield  of  nitrogen 
as  ammonia  depends  on  the  amount  of  steaming  given. 

A  modified  method  of  laboratory  analysis,  which  allows 
both  oil  and  ammonia  yield  to  be  determined  simultaneously, 
is  described  by  lyomax  and  Remfry  (J.I.P.T.  vol.  7, 
1921,  p.  36).  These  two  investigators  have  noticed  the 
surprising  fact  that  the  changes  which  take  place  during 
the  weathering  of  shale  affect  to  a  considerable  extent  the 
obtainable  yield  of  oil.  After  a  short  period  of  exposure 
to  the  weather,  the  oil  yield  is  found  to  improve  by  as  much 
as  20  per  cent,  in  some  cases,  but  after  longer  exposure 
falls  again,  reaching  its  original  value  in  the  course  of  a 
month  or  two  and  then  falling  still  lower.  It  is  evidently 
important  to  seize  the  right  moment  for  retorting  the  shale. 


SECTION  D.— THE  RETORTING   OF   OIL 
SHALES 

As  the  oil  obtained  from  oil  or  pyrobituminous  shales  does 
not  exist  as  such  in  the  shale,  but  is  formed  during  the 
process  of  retorting,  the  questions,  what  takes  place  in  the 
retorting  process,  and  how  far  the  conditions  of  retorting 
affect  the  yield  and  quality  of  the  product,  are  of  the  very 
greatest  importance. 

It  has  long  been  recognized  that  the  changes  taking  place 
in  the  retort  are  of  a  twofold  nature,  viz.  (i)  the  production 
of  certain  volatile  compounds  by  the  thermal  decomposition 
of  the  pyrobituminous  constituents  of  the  shale,  and  (2)  the 
subsequent  cracking  or  further  decomposition  of  these 
primary  volatile  products.  It  has  also  been  regarded  as 
probable  that  considerable  chemical  changes  take  place 
by  the  action  of  heat  even  before  the  above-named  primary 
volatile  products  make  their  appearance,  and  recently  this 
view  has  been  experimentally  verified.  Messrs.  McKee 
and  Lyder  (/.  Ind.  and  Eng.  Chem.,  1921,  613,  678)  have 
studied  this  point  and  have  shown  that  whereas  the  pyro- 
bituminous constituents  of  the  original  shale  are  scarcely 
soluble  in  neutral  organic  solvents  such  as  carbon  bisulphide, 
if  the  shale  is  heated  for  some  time  at  a  temperature  just 
below  that  at  which  volatile  products  are  evolved  in  appreci- 
able amount,  the  pyrobituminous  portion  undergoes  change 
into  a  heavy  bitumen  which  is  then  for  the  most  soluble  in 
carbon  bisulphide.  In  the  case  of  a  certain  Colorado  shale 
which  they  investigated,  this  first  resolution  of  the  original 
pyrobituminous  matter  into  simpler  but  still  very  complex 
substances  took  place  at  temperatures  of  400°  to  410°  C., 
and  a  slight  further  increase  of  the  temperature  above 

in 


H2    PETROLEUM  AND  ALLIED  INDUSTRIES 

410°  brought  about  cracking  and  the  production  of  light 
hydrocarbons. 

These  results  verify  the  above-mentioned  view  that  two 
quite  distinct  sets  of  chemical  reactions  take  place  in  the 
process  of  retorting.  The  retort  functions  not  only  as  a 
producer  of  a  bituminous  substance,  but  also  as  a  cracking 
still. 

Two  distinct  reactions  thus  take  place,  the  second 
following  closely  on  the  heels  of  the  first.  It  is,  however,  of 
importance  that  the  second  stage,  viz.  the  cracking,  should 
be  under  control  to  some  extent  at  any  rate.  The  question 
of  the  control  of  this  cracking  is,  therefore,  one  of  the  most 
important  factors  which  should  influence  retort  design. 

As  all  pyrobituminous  shales  leave  a  more  or  less  carbon- 
aceous residue  on  retorting,  the  question  of  the  utilization 
of  this  carbon,  and  also  of  the  nitrogen  contained  in  the 
residue  is  also  of  great  importance. 

This  may  be  effected  by  the  introduction  of  steam  alone 
where  the  carbon  content  of  the  residue  is  low,  or  of  steam 
with  a  limited  amount  of  air  where  the  carbon  content  is 
higher,  into  the  bottom  of  the  retort  whereby  the  residue 
is  converted  into  water  gas  or  producer  gas  and  ammonia, 
the  latter  being  recovered  in  the  well-known  manner,  and  the 
former  mixing  with  the  gas  formed  from  the  bituminous 
matter.  This  gas  after  separation  of  the  oils  is  used  for 
heating  the  retorts  or  other  purpose  if  there  is  any  surplus. 
In  addition,  however,  such  water  gas  or  producer  gas  produc- 
tion has  a  marked  effect  on  the  oil  production  of  the  shale, 
as  the  sensible  heat  of  this  gas  assists  largely  in  the  thermal 
decomposition  of  the  shale  through  which  it  passes,  thus 
considerably  reducing  the  time  required  for  completion  of 
the  elimination  of  the  oil  from  it.  When  the  percentage  of 
carbon  in  the  residue  is  fairly  high,  the  sensible  heat  in  the 
producer  gas  thus  made  is  in  itself  sufficient  to  effect  the 
removal  of  all  the  volatile  matter  from  the  shale,  and  no 
external  heating  of  the  retort  is  required. 

Such  production  of  water  gas  or  producer  gas  within  the 
retort  has  the  further  result  that  the  primary  oil  vapours  are 


THE  RETORTING  OF  OIL  SHALES          113 

removed  from  the  zone  of  heat  more  rapidly,  and  the  crude 
oil  produced  contains  a  larger  proportion  of  saturated  hydro- 
carbons. The  decomposition  of  the  shale  and  the  subsequent 
cracking  of  the  primary  vapours  also  then  take  place  in  an 
atmosphere  containing  a  much  larger  proportion  of  hydrogen 
and  steam,  and  this  further  favours  the  production  of  satu- 
rated Irydrocarbons,  and  consequently  improved  quality  of 
the  crude  oil  obtained. 

Certain  disadvantages  follow  from  such  production  of 
water  gas  or  producer  gas  in  the  retorts,  although  these  are 
far  outweighed  by  the  above-mentioned  advantages.  Thus 
the  higher  production  of  gas  involves  a  greater  cost  for  con- 
densing and  scrubbing  apparatus,  and  the  large  volume  of 
gas  carries  away  from  the  condenser  most  of  the  lighter 
hydrocarbons  in  the  form  of  vapour,  making  their  recovery 
by  oil-washing  more  expensive. 

The  principal  points  to  be  borne  in  mind  when  considering 
the  design  and  functions  of  a  retorting  plant  are — 

(a)  The  carrying  out  of  the  initial  stages  of  the  distillation 
at  as  low  a  temperature  as  possible.     This  is  necessary  in 
order  to  obtain  relatively  large  oil  and  small  gas  yields,  and 
to  obtain  oil  of  paraffinous  rather  than  of  aromatic  nature. 

(b)  Efficient   arrangements   for   removing   the   vapours 
from  the  retort  as  soon  as  possible,  and  for  ensuring  that  they 
come  into  contact  with  highly  heated  shale  and  retort  walls 
as  little  as  possible,  in  order  to  avoid  secondary  reactions 
and  cracking  or  decomposition  of  the  oils  first  formed. 

(c)  The  necessity  of  ensuring  efficient  transfer  of  heat 
through  the  mass  of  shale  to  be  retorted.     As  the  shale 
is  such  a  poor  conductor  of  heat,  either  the  layer  of  shale  in 
the  retort  must  not  be  more  than  a  few  inches  in  thickness, 
or  mechanical  means  of  keeping  the  shale  in  motion  must  be 
adopted. 

(d)  Arrangements  for  enabling  the  shale  to  be  further 
distilled  in  contact  with  steam,  either  in  the  same  or  in  a 
separate  retort,  in  order  to  obtain  the  maximum  ammonia 
yield. 

(e)  The  problem  common  to  all  plants,  that  of  efficient 
p.  8 


ii4    PETROLEUM  AND  ALLIED  INDUSTRIES 

utilization  of  heat  as  far  as  possible,  i.e.  minimum  fuel 
consumption. 

(/)  Simplicity  of  operation  and  control. 

(g)  Capacity  for  working  continuously  over  long  periods, 
with  high  rate  of  throughput  and  low  maintenance  costs. 

(h)  I,ow  initial  capital  expenditure. 

In  the  case  of  plants  for  the  low-temperature  distillation 
of  coal,  or  at  any  rate  of  caking  coals,  the  difficulties  caused 
by  the  caking  into  a  sticky  mass  of  the  intumescing  coal 
and  its  consequent  inability  to  pass  down  the  retort,  are  so 
great  that,  up  to  the  present,  no  really  good  type  of  retort 
has  been  handled  for  dealing  with  such  coals. 

McKee  and  lyyder  have  also  determined  some  data, 
which  will  be  useful  for  designers  of  shale  retorts. 

The  heat  required  to  convert  the  kerogen  into  oil  was 
found  to  vary  from  421  to  484  calories  per  gram  of  oil  and 
gas  produced,  in  the  cases  of  the  three  shales  investigated 
by  them.  The  heat  conductivity  of  the  shale  was  found  to  be 
0*00086  in  c.g.s.  units  and  the  specific  heat  about  0*265. 

Outside  of  Scotland,  few  shale-oil  works  of  any  large 
capacity  exist.  It  will  be  as  well,  therefore,  to  describe 
the  retorting  process  as  used  in  Scotland,  before  considering 
the  very  numerous  types  of  retorts  designed  and  patented, 
but  so  far  not  found  working  in  practice  on  a  large  scale. 

The  shale  is  first  broken  up  into  small  pieces  before 
being  fed  into  the  retort  hoppers.  The  type  of  crusher  used 
depends  to  a  large  extent  on  the  nature  of  the  shale.  The 
tough  Scottish  shales  are  broken  up  in  a  heavy  toothed 
roller  machine.  For  more  brittle  shales  a  head  motion  jaw- 
crusher  will  prove  more  satisfactory.  In  crushing  shales 
any  rubbing  or  grinding  movement  should  be  avoided  in 
order  to  minimize  the  production  of  dust  or  fines,  as  the 
presence  of  dust  gives  trouble  owing  to  the  clogging  up  of 
the  condensing  plant. 

The  shale  retorts  employed  in  the "  Scottish  shale-oil 
industry  are  all  modified  forms  of  the  original  Young  and 
Beilby  continuous  vertical  retort  brought  out  in  1882. 
One  of  the  most  successful  of  these  is  the  Pumpherston 


THE  RETORTING  OF  OIL   SHALES          115 

or  Bryson  type.     This  retort  is  made  up  of  two  parts 
The  upper  is  of  cast  iron,  15  feet  long,  2  feet  in  diameter 
at  the  top,  tapering  to  2  feet  4  inches  at  the  lower  end.    The 


Y///////////, 
\\\\\\\\ 

FIG.  1 6. — Bryson  shale  retort. 

lower  portion  is  of  firebrick,  20  feet  in  length,  2  feet  4  inches 
diameter  at  the  top  where  it  joins  the  cast-iron  upper  part 
tapering  to  3  feet  at  its  lower  end.  This  retort  is  circular 
in  cross  section.  A  few  inches  below  the  lower  end  of  the 


n6    PETROLEUM  AND  ALLIED  INDUSTRIES 

retort  is  a  circular  table  on  which  the  spent  shale  rests.  On 
this  table  works  a  revolving  arm  which  slowly  scrapes  the 
spent  shale  over  the  edge  of  the  table,  thus  providing  con- 
tinuous removal  of  the  spent  shale  from  the  retort,  enabling 
supplies  of  fresh  shale  to  be  fed  in  continuously  through  the 
hopper  at  the  top. 

The  upper  iron  portion  of  this  retort  is  kept  at  a  dull 
red  heat,  and  it  is  in  this  section  that  the  oil  distillation 
takes  place.  The  oil  vapours  pass  out  just  below  the  hoppers, 
into  a  large  main. 

In  the  lower  firebrick  portion  of  the  retort  the  shale 
is  subjected  to  a  higher  temperature  in  presence  of  steam,  the 
carbon  of  the  residue  being  converted  into  carbon  monoxide, 
and  the  nitrogen  partly  into  ammonia,  this  part  of  the 
retort  thus  functioning  as  an  ammonia  and  gas  producer. 

With  a  retort  of  the  above  dimensions  about  4  to  5  tons 
per  day  of  shale  yielding  say  25  gallons  per  ton  of  oil  can  be 
handled.  For  each  gallon  of  oil  produced  about  4  gallons 
of  water  in  the  form  of  exhaust  steam  is  introduced  into  the 
bottom  of  the  retort.  This  steam  serves  several  purposes  ; 
it  absorbs  a  certain  amount  of  heat  from  the  spent  shale, 
produces  water  gas  from  the  fixed  carbon  left  in  the  shale 
after  distillation,  produces  ammonia  (about  60  per  cent,  of 
the  total  nitrogen  of  the  shale  being  so  recovered),  helps 
to  equalize  temperatures  throughout  the  cross  section  of 
the  retort  and  to  carry  off  the  vapours.  A  discussion  of  the 
action  of  steam  on  yield  of  ammonia  in  this  connection  is 
given  by  A.  J.  Franks  in  Chemical  and  Metallurgical 
Engineering  for  December  15,  1920,  p.  1149.  Franks 
points  out  that  the  steam  has  a  synthetic  action  at  high 
temperatures  and  that  it  removes  the  ammonia  so  formed 
before  decomposition  can  take  place  to  any  great  extent, 
the  rate  of  dissociation  of  ammonia  at  the  temperatures  in 
question  being  low. 

The  quality  of  the  oil  obtained  depends  on  the  temper- 
ature employed  in  retorting.  The  higher  the  temperature 
the  greater  the  proportion  of  unsaturated  hydrocarbons  in 
the  oil,  the  greater  the  subsequent  loss  in  refining  the  crude 


THE  RETORTING  OF  OIL  SHALES          117 

oil,  and  the  lower  the  proportion  of  paraffin  wax  (Stewart, 
J.S.C.I.,  1889,  p.  100). 

The  gases  evolved  after  passing  through  the  scrubbers 
and  condensers  are  used  for  heating  the  retorts,  no  extra 
fuel  being  necessary. 

There  are  three  other  types  of  retort  in  use  in  Scotland, 
viz.  the  Henderson,  Young  and  Fyfe,  and  the  Crichton. 
These  are  all  similar  in  principle,  being  based  on  the  original 
Young  and  Beilby  retort. 

Although  such  retorts  have  given  very  satisfactory 
results  with  Scottish  shales,  it  by  no  means  follows  that  they 
can  be  applied  with  equal  success  to  all  shales,  as  shales  from 
different  localities  exhibit  very  great  differences  in  character. 
Nor  may  it  be  taken  for  granted  that  these  types  are  the 
best  possible  even  for*-Scottish  shales.  The  throughput  per 
retort  is  very  low  and  the  capital  expenditure  on  plant 
therefore  high.  The  chief  difficulty  in  designing  a  vertical 
gravity  feed  retort  of  this  type  arises  out  of  the  low  thermal 
conductivity  of  the  shale.  If  the  centre  of  the  mass  under- 
going distillation  be  more  than  a  few  inches  from  the  retort 
wall,  the  heat  transference  is  so  poor  that  either  the  internal 
mass  does  not  attain  a  temperature  sufficiently  high,  or  the 
portions  of  the  shale  near  the  retort  wall  are  subjected  to  a 
temperature  too  high,  resulting  in  excessive  cracking  of  the 
oil  and  diminished  yield. 

Numerous  other  types  of  retorts  have  been  devised, 
few  of  which  have  passed  and  many  of  which  have  never 
reached  the  large-scale  experimental  stage.  These  types 
may  be  divided  into  classes — 

(a)  Continuous  vertical  with  gravity  feed  (the  Scottish 
type). 

(b)  Continuous  vertical  type  with  some  form  of  mechanical 
feed. 

Examples  of  this  type  are  the  Colorado  continuous, 
fitted  with  a  helical  conveyor,  and  the  Simpson,  fitted  with 
a  means  of  keeping  the  charge  in  continuous  movement 
by  means  of  two  revolving  rollers  at  the  base  of  the 
retort.  An  interesting  retort  of  this  class  is  that  recently 


n8    PETROLEUM  AND  ALLIED  INDUSTRIES 

designed  by  Freeman  (Pet.  Times,  January  14,  1922,  p.  43). 
This  retort  is  made  up  of  a  number  of  distinct  chambers 
set  vertically  one  above  the  other.  Each  chamber  is 
separately  heated  by  gas  burners  and  the  temperature  is 
accurately  controlled  by  a  special  automatic  apparatus. 
The  finely  divided  shale  rests  on  a  revolving  table  in  each 
chamber  and  is  transferred  gradually  from  one  chamber  to 
the  next  below  it  by  means  of  revolving  arms,  the  action 
being  similar  to  that  of  a  pyrites  burning  oven.  Each 
chamber  is  provided  with  separate  vapour  off-take  pipes. 
One  advantage  which  this  retort  possesses  is  that  of  the 
driving  off  of  the  water  mostly  in  the  first  chamber  so  that 
emulsified  oil  distillates  are  largely  avoided. 

(c)  Horizontal  continuous  types  fitted  with  mechanical 
feed. 

Examples  of  this  are  the  Del  Monte,  a  tubular  externally 
heated  retort  fitted  with  an  internal  worm,  and  the  Thyssen, 
the  retort  being  slightly  inclined  and  revolving  like  a  cement 
kiln,  but  with  external  heating. 

(d)  Horizontal  continuous  type  fitted  with  mechanical 
feed  and  internal  heating,  e.g.  the  Burney  retort.    This  is  of 
several  feet  diameter,  and  is  fitted  with  a  large  internal  screw, 
through  the  vanes  of  which  the  heating  gases  pass,  the 
difficulty  of  heat  transmission  thus  being  to  some  extent 
avoided. 

(e)  Types  in  which  the  heating  is  effected  internally  and 
directly  by  means  of  the  sensible  heat  of  gases. 

Examples  of  this  are  the  Maclaurin  type  which  has  had 
some  success  even  when  applied  to  the  low-temperature 
distillation  of  coal,  and  the  Nielsen,  which  consists  of  an 
inclined  rotating  cylinder,  in  which  the  shale  is  heated  by 
direct  contact  with  the  heated  gases  from  a  producer  in 
which  a  part  of  the  carbonaceous  residue  is  treated. 

A  summary  of  the  forms  of  plant  used  or  under  trial  in 
America  for  shale  retorting  is  given  in  the  Chemical  Age, 
New  York,  Januan^,  1921,  vol.  29,  p.  30. 

As  practically  all  oil -shale  retorts,  with  the  exception  of 
those  used  in  Scotland,  are  as  yet  in  the  experimental  stage, 


THE  RETORTING  OF  OIL  SHALES         119 

the  writer  feels  that  no  opinion  of  value  as  to  their  relative 
merits  can  as  yet  be  formed. 

It  would  appear,  however,  that  retorts  constructed  on 
the  principle  of  heating  by  direct  contact  with  heated  gases, 
products  of  combustion,  or  better,  heated  combustible  gases 
from  a  producer,  could  be  constructed  of  large  dimensions 
with  great  potentialities  as  to  throughput,  the  difficulties 
dependent  on  the  low.  thermal  conductivity  of  the  shale 
being  in  such  cases  overcome.  One  objection  to  this  type 
is  the  dilution  of  the  oil  vapours  with  large  volumes  of 
gases,  which  renders  condensers  of  greater  capacity 
necessary  (Simpson,  "  Plant  Design  for  Hot  Gas  Pyrolytic 
Distillation  of  Shale,"  Chem.  and  Met.  Eng.,  1921,  p.  341). 

The  issuing  gases  and  vapours  from  the  retorts  are  often 
passed  through  some  form  of  centrifugal  separator,  their 
temperature  being  kept  above  100°  C.  The  heavier  portions 
of  the  distillate  are  thus  collected  free  from  water.  The 
remainder  of  the  vapours  are  then  condensed  in  water-cooled 
condensers,  then  passed  through  scrubbers  in  contact  with 
sulphuric  acid  for  the  purpose  of  removing  ammonia,  then 
through  scrubbers  in  contact  with  heavy  oil,  to  which  the 
vapours  give  up  the  last  traces  of  volatile  fractions.  The 
residual  gas  leaving  the  scrubbers  is  used  for  heating  the 
retorts  or  for  other  purposes  in  the  works. 


GENERAL   REFERENCES  TO   PART   IV.,   SECTION   D. 

Ells,  "  Bituminous  Oil  Shales  of  New  Brunswick  and  Nova  Scotia." 
Canada  Department  of  Mines. 

Greene,  "  Treatise  on  British  Mineral  Oils."     Griffin  and  Co. 
Scheithauer,  "  Shale  Oil  and  Tars."     Scott,  Greenwood  and  Co. 
Stewart,  "  Oil  Shales  of  the  Lothians."    Memoir  of  Geological  Survey. 


SECTION  E.— THE   CHARACTERS   OF  SHALE 

OILS 

THE  crude  oils  derived  from  the  retorting  of  shales  exhibit 
great  differences  in  character,  dependent  on  (a)  the  nature  of 
the  pyrobituminous  organic  matter  of  the  shale,  and  on 
(b)  the  conditions  under  which  retorting  is  effected. 
Although  resembling  to  some  extent  crude  petroleums, 
shale  oils  usually  exhibit  special  characters  in  consequence 
of  their  relatively  high  content  of  unsaturated  hydrocarbons. 

The  method  of  determining  the  unsaturated  hydro- 
carbons present  is  somewhat  rough  and  ready,  but  serves 
the  purpose  sufficiently  well.  The  crude  oil  is  treated  with 
two  volumes  of  sulphuric  acid  (sp.  gr.  1-84)  and  allowed  to 
settle  out.  The  volume  of  the  oil  remaining,  expressed  in 
percentage  of  the  volume  of  oil  taken,  gives  the  percentage 
of  saturated  hydrocarbons.  The  difference  is  not  strictly 
due  to  the  absorption  of  unsaturated  hydrocarbons  only, 
as  basic  nitrogen  compounds  may  be  present,  certain 
aromatic  hydrocarbons  may  be  absorbed,  and  certain  com- 
pounds may  be  polymerized  and  subsequently  dissolved  by 
the  sulphuric  acid. 

A  number  of  shale  oils  examined  in  the  laboratory  of 
the  Colorado  School  of  Mines  (C.  W.  Botkin,  Chem.  and  Met. 
Efig.,  1921,  p.  876)  gave  the  following  results  : — 

Shale  Per  cent,  of  saturated 

retorted.  hydrocarbons  in  the  oil. 

Colorado  . .          . .          . .  13-6  to  28 '0 

Utah 15-8  to  26-5 

Nevada  . .          . .          . .  41  '2 

Kngland  . .          . .          . .  16*0 

vScotland  . .          . .          . .  38-0 

The  high  content  of  unsaturated  hydrocarbons  as 
compared  with  petroleums  is  due  to  the  low  content  of 

120 


THE   CHARACTERS  OF  SHALE  OILS        121 

hydrogen  of  the  kerogen,  there  being  insufficient  to  combine 
with  the  carbon.  Even  although  so  large  a  proportion  of 
unsaturated  hydrocarbons  are  produced,  there  is  always 
free  carbon  left  in  the  shale  residue. 

The  ratio  of  carbon  to  hydrogen  for  the  kerogens  of 
shales  varies  approximately  from  7  to  8  or  more,  whereas 
the  ratio  for  paraffins,  such  as  are  usual  in  petroleum,  varies 
from  5  to  6.  Moreover,  it  is  probable  that  some  of  the 
saturated  hydrocarbons  formed  during  the  distillation 
undergo  secondary  cracking,  with  the  further  production  of 
unsaturated  hydrocarbons. 

The  probability  of  this  cracking  indicates  the  necessity 
for  designing  the  plant  and  carrying  out  the  retorting  so 
as  to  remove  the  products  of  distillation  as  soon  as 
formed. 

A  series  of  experiments  to  investigate  the  influence  of 
temperature  in  retorting  and  the  influence  of  steam  or 
hydrogen  gas  were  carried  out  on  Colorado  shale  oil  in  the 
laboratory  of  the  Colorado  School  of  Mines  (Quarterly  of  the 
Colorado  School  of  Mines,  vol.  16,  No.  2,  April,  1921). 

Retorting  was  carried  out  under  four  different  conditions  : 
(a)  at  low  temperature  without  use  of  steam,  (b)  at  low 
temperature  with  use  of  steam,  (c)  at  low  temperature  with 
hydrogen  in  place  of  steam,  (d)  at  higher  temperatures,  the 
oil  being  partly  returned  to  the  retort  by  means  of  a  reflux 
condenser  so  as  to  obtain  good  cracking  conditions. 

It  was  found  that  under  none  of  these  conditions  was 
(i)  oil  obtained  from  that  particular  shale  containing  less 
than  70  per  cent,  of  unsaturated  hydrocarbons.  This  is,  of 
course,  primarily  due  to  the  low  hydrogen  content  of  this 
shale.  (2)  That  the  presence  of  free  hydrogen  had  no  effect 
other  than  that  of  diluting  and  assisting  in  the  removal  of 
the  vapours,  a  function  performed  equally  well  by  steam. 
(3)  That  when  the  cracking  is  minimized  by  the  use  of  steam, 
the  unsaturated  hydrocarbons  are  actually  about  15  per 
cent,  higher  than  when  the  cracking  is  at  its  maximum. 
This  latter  result  is,  at  first,  rather  surprising,  but  it  is 
explained  by  the  fact  that  the  yield  of  oil  is  10  per  cent. 


122    PETROLEUM  AND  ALLIED  INDUSTRIES 

less,  owing  to  the  cracking  of  unstable,  unsaturated  hydro- 
carbons with  the  formation  of  coke  and  some  lighter 
saturated  oils.  This  is  an  extremely  interesting  result  as  it 
indicates  that  it  may  be  more  economical  to  retort  at  higher 
temperatures,  the  loss  in  yield  of  crude  oil  being,  perhaps, 
counterbalanced  by  the  lower  loss  in  the  subsequent  refining 
operations.  , 

These  conclusions  were  further  borne  out  by  the  be- 
haviour of  the  resulting  oils  on  distillation.  The  oil  obtained 
by  the  low-temperature  steam  distillation  containing  85*4 
per  cent,  of  unsaturated,  cracked  to  the  greatest  extent, 
yielding  10  per  cent,  of  coke,  2*95  per  cent,  of  gas,  and  86*6 
per  cent,  of  oil  containing  only  65  per  cent,  of  unsaturated 
hydrocarbons. 

This  work  was  followed  up  by  an  examination  of  the 
effect  of  distillation  on  various  shale  oils,  from  which  the 
following  conclusions  were  drawn :  (i)  There  is  a  large 
amount  of  decomposition  during  the  subsequent  distillation 
of  the  crude  oil,  this  being  least  for  parairmous,  and  most 
for  asphaltic  oils.  (2)  The  cracking  is  most  rapid  when  the 
still  temperature  exceeds  320°  C.  (3)  That  the  once  run 
oils  are  more  stable  and  suffer  relatively  little  cracking  on 
further  distillation.  (4)  That  the  decomposition  is  appar- 
ently one  of  heavy  unsaturated  compounds,  which  are 
unstable  at  the  still  temperatures  necessary  for  distillation 
at  atmospheric  pressure,  without  the  introduction  of  steam. 
Stewart,  "  Oil  Shales  of  the  lyOthians,"  Memoir  of 
Geological  Survey,  Scotland,  pp.  155-157,  gives  data  re  the 
character  of  several  crude  oils  from  Scottish  shales — 
Specific  gravity  . .  . .  . .  from  0*864  to  0*909 

Setting  point        ,,67°  F.  to  93°  F. 

Benzine  fraction  0730/0740      . .     up  to  4*65% 
Burning  oil  0*807/0-812  . .          . .     15*92%  to  40-59% 

Medium  oil  0*840. .          . .          . .     up  to  9*18% 

Imbricating  oil  0*865/0 '885        . .         ,,      34-02% 
Solid  paraffin  114/116°  F.          . .     about  10%  to  15% 
Loss  in  refining    . .  . .     24-55%  to  35*94% 

It    will    be   noted   that   the   loss   in   refining   is   many 


THE   CHARACTERS   OF  SHALE  OILS        123 

times  greater  than  that  incurred  in  working  up  a  crude 
petroleum. 

A  sample  of  Kimmeridge  shale  oil  was  found  to  have  the 
following  properties  : — 

Specific  gravity    . .          . .         . .     1*009 

Sulphur 5  -8  per  cent. 

Viscosity  Redwood  I.  at  70°  F.        62  seconds 

Engler  at  20°  C.         . .     2  '2 
Paraffin  wax        . .         . .         . .     1/2  per  cent. 

Fraction  to  150°  C.         . .         . .     Sp.   gr.   0-867.    Sulphur 

7 '2  per  cent.  Saturated 

hydrocarbons    10    per 

cent. 
Fraction  150°  C.  to  270°  C.        . .     Sp.    gr.    0-936.     Sulphur 

4 'i  per  cent. 
Residue  54  per  cent Sp.   gr.    ro6o.    Sulphur 

4-1  per  cent.    Viscosity 

Eng.   at  20°  C.    over 

200°. 

A  sample  of  fuel  oil  from  Scottish  shale  oil  was  found  to 
possess  the  following  characters  : — 

Specific  gravity  at  15°  C.  . .  1*009 

Sulphur     . .         . .         . .         . .  0*46  per  cent. 

Calorific  value     ' 8347,  i.e.  15,025  B.Th.Us. 

Flash-point  140°  F. 

Viscosity  Redwood  I.  at  70°  F.  37  seconds 

Tar  acids  . .         . .         . .         . .  30  per  cent,  by  volume. 

The  low  calorific  value  is  to  be  attributed  to  the  high 
percentage  of  tar  acids. 

It  will  thus  be  seen  that  shale  oils  differ  materially  in 
character  from  crude  petroleums.  The  presence  of  large 
proportions  of  unsaturated  hydrocarbons,  renders  their 
refining  into  commercial  products  a  difficult  proposition,  as 
chemical  reagents,  which  might  be  employed  to  remove 
undesirable  sulphur  compounds,  will  also  -attack  the  un- 
saturated compounds.  Moreover,  unsaturated  hydrocarbons 


124    PETROLEUM  AND  ALLIED  INDUSTRIES 

are  unstable,  and  water-white  sweet  products  made  from 
them  are  very  liable  to  change  on  standing.  The  quality  of 
a  shale  oil  is  thus  in  the  present  state  of  our  knowledge 
determined  chiefly  by  its  content  of  unsaturated  hydro- 
carbons. If  some  process  of  commercially  converting  un- 
saturated into  saturated  hydrocarbons  were  only  known, 
the  problem  of  the  satisfactory  utilization  of  many  shale 
oils  would  be  much  nearer  solution.  The  methods  of 
working  up  Scottish  shale  oil  are  in  the  main  those  usually 
employed  in  petroleum  refining,  for  which  reference  may 
be  made  to  Part  VII. 


SECTION  R— VARIOUS  TARS 

UNDER  the  term  "  tars  "  may  be  grouped  a  number  of  products 
resulting  from  the  distillation  of  coal,  lignite,  peat,  wood,  or 
other  organic  material.  Such  products  are  described  as 
tars  because,  in  addition  to  hydrocarbons,  they  contain 
large  proportions  of  other  bodies  such  as  phenols  and 
nitrogen  bases.  Moreover,  their  hydrocarbon  constituents 
are  often  very  different  from  those  normally  occurring  in 
petroleum.  The  chief  examples  of  this  class  are  the  tars 
derived  from  the  carbonization  of  coal  under  various  con- 
ditions, e.g.  horizontal  coal  tar,  vertical  coal  tar,  low- tempera- 
ture coal  tar,  and  coke-oven  tar,  together  with  tars  such  as 
Mond-gas  tar  and  blast-furnace  tar.  Tars  resulting  from 
the  distillation  of  peat,  lignite,  wood,  etc.,  are  of  less  common 
occurrence. 

As  the  subjects  of  the  production  of  tars  or  liquid  fuels 
from  coal,  lignite,  peat,  and  wood,  have  been  dealt  with  in 
the  book  of  this  series  of  H.  S.  Taylor  on  "  Fuel  Production 
and  Utilization,"  little  need  be  said  here.  A  description  of 
the  methods  adopted  for  the  distillation  of  coal  in  coke 
ovens  or  low-temperature  carbonization  retorts  is  quite 
beyond  the  scope  of  this  work.  The  reader  may  be  referred 
to  such  works  as  V.  B.  I^ewes,  "  The  Carbonization  of  Coal," 
Benn  Brothers.  The  subject  of  low- temperature  carboniza- 
tion of  coal  has  received  much  attention  during  the  last  few 
years,  but  its  successful  commercial  development  has  not 
yet  been  assured.  Apart  from  the  questions  of  marketing 
of  the  solid  carbonaceous  residues,  and  the  low-temperature 
tars,  the  engineering  difficulties  of  designing  suitable  retorting 
plant,  especially  in  the  case  of  caking  coals,  are  much  greater 
than  those  met  with  in  the  designing  of  plant  for  the 
distillation  of  pyrobituminous  shales.  In  character  the  various 

125 


126    PETROLEUM  AND  ALLIED  INDUSTRIES 


tars  resulting  from  the  distillation  of  coals  of  different  types 
under  various  conditions  are  intermediate  between  ordinary 
horizontal  coal  tar  on  the  one  hand,  and  crude  petroleum  on 
the  other.  The  character  of  these  tars  can  best  be  explained 
by  comparison  with  these  two  extreme  types. 

In  general,  the  character  of  a  coal  tar  depends  on  the 
temperature  at  which  carbonization  takes  place.  The  tars 
derived  from  horizontal  gas-works  retorts,  which  are 
operated  at  high  temperatures,  are  rich  in  aromatic  hydro- 
carbons and  practically  paraffin  free;  those  from  low- 
temperature  carbonization  are  rich  in  paraffin,  and  poor  in 
aromatics.  Coke-oven  tars,  and  tars  from  vertical  gas-works 
retorts  are  intermediate  in  character  between  these  two 
extreme  types. 

This  difference  in  character  is  largely  due  to  the  secondary 
reactions  which  take  place  in  the  highly  heated  horizontal 
retorts,  the  paraffin  hydrocarbons  first  formed  being  cracked 
into  aromatic  hydrocarbons,  hydrogen,  and  coke.  In 
consequence  of  this,  high-temperature  tars  are  relatively 
rich  in  so-called  "  free  carbon,"  insoluble  in  carbon  bisulphide, 
low-temperature  tars  containing  sometimes  as  little  as 
one  per  cent. 

I,ow-temperature  tars  are  richer  in  tar  acids,  the  cresols 
and  higher  homologues  predominating  over  phenol. 

High-temperature  tars  contain  much  naphthalene,  low- 
temperature  tars  little  or  none. 

The  nitrogen  of  high-temperature  tars  is  largely  in  the 
form  of  pyridin  homologues,  of  low-temperature  tars  largely 
in  the  form  of  aniline. 

The  following  table  indicates  the  chief  points  of  difference 
between  these  tars  : — 


Sp.gr. 

Per 
cent,  tar 
acids. 

Per 
cent, 
free 
carbon. 

Per 

cent, 
naph- 
thalin. 

Aroma- 
tic con- 
tent. 

Per 
cent, 
pitch. 

Horizontal 

I'22 

3 

2O 

10-15 

rich 

65 

Coke  oven 

ri8 

5 

12 

10 

60-65 

Vertical    
Low-temp,  carbonization 

I'lO 

7 

12 

4 

2 

5-10 
o 

\ 

r 

40-50 

Peat         

o-99 

10 

I 

0 

poor 

3° 

VARIOUS   TARS  127 

The  above  figures  are  approximations  only,  and  may 
serve  merely  to  indicate  the  general  relations  of  the  various 
tars.  The  characters  of  individual  tars  of  any  one  class 
show  great  variation. 

The  fundamental  difference  between  such  tars  as  a  whole 
and  crude  petroleum  is  indicated  also  by  their  elementary 
analysis.  The  ratio  of  the  content  of  carbon  to  that  of 
hydrogen  ranges  from  8  to  n  for  the  tars,  whereas,  even 
for  heavy  petroleum  it  is  not  more  than  8,  and  for  the  lighter 
as  low  as  5*5.  This,  relative  shortage  of  hydrogen,  together 
with  the  presence  of  oxygen,  is  the  chief  cause  of  the  great 
difference  between  tars  and  petroleum  oils.  Tars  of  the  low- 
temperature  type  may  yield  small  percentages  of  light 
hydrocarbons  suitable  for  motor  use.  After  these  have 
been  removed  the  residue  is  only  fit  for  use  as  liquid  fuel,  at 
the  present  day  at  any  rate. 

Such  tars  serve  as  reasonable  fuels  for  furnace  use. 
Their  calorific  powers  are,  however,  relatively  low  compared 
to  those  of  petroleum  fuels,  say  16,000  as  compared  with 
18,000  B.Th.U.  Owing  to  their  content  of  pitch  they  cannot 
be  blended  with  a  fuel  of  petroleum  origin,  owing  to  the 
precipitation  of  the  pitch.  Such  low-temperature  tars  may 
also  be  successfully  used  as  diesel  engine  fuel.  In  addition  to 
low-temperature  tars  made  by  the  direct  distillation  of  coal, 
other  types  such  as  producer-gas  tar,  which  is  condensed  out 
of  producer  gas,  blast-furnace  tar,  condensed  out  of  blast- 
furnace gases,  and  Mond-gas  tar  from  Mond-gas  producers, 
are  also  produced  in  relatively  small  quantities.  These  tars 
are  similar  in  their  general  character  to  low-temperature 
tars  and  need  not  be  further  described. 

In  Saxony  there  exists  quite  a  considerable  industry, 
dependent  on  rather  peculiar  types  of  lignite.  These 
lignites  contain  a  bituminous  material  which  is  soluble  in 
solvents,  such  as  benzene,  carbon  tetrachloride,  ether,  or 
acetone.  The  material  so  extracted  is  utilized  for  the 
preparation  of  montan  wax,  which  is  described  in  Part  VI. 
These  lignites  on  distillation  yield  tars  rich  in  paraffin 
wax.  When  raised  from  the  mine  these  bituminous 


128    PETROLEUM  AND  ALLIED  INDUSTRIES 

lignites  present  a  greasy  brownish  appearance,  and  dry  to  a 
lighter  colour,  the  richest  of  them,  viz.  the  peculiar  material 
termed  "  p}aopissite "  being  yellow  in  colour.  This  has 
a  specific  gravity  of  about  ro,  whereas  ordinary  or  pyro- 
bituminous  lignites  have  specific  gravities  ranging  from 
i  '2  to  1-4. 

Various  types  of  retort  have  been  used,  the  most  successful 
being  that  devised  by  Rolle,  which  works  continuously. 
This  retort  consists  of  a  cylindrical  firebrick  structure 
about  20  feet  high  and  5  to  6  feet  internal  diameter.  Inside 
this  cylindrical  retort  is  built  up  a  series  of  bevelled  iron 
rings  superimposed  one  on  the  other,  forming  an  internal 
core  or  cylindrical  chamber,  the  surface  of  which  presents 
the  appearance  of  louvre  boards.  The  lignite  is  fed  by 
means  of  a  hopper  into  the  annular  space  between  the 
central  cast-iron  chamber  and  the  outer  firebrick  cylinder. 
Distillation  is  effected  in  this  annular  space  by  the  heat 
transmitted  through  the  walls  of  the  outer  cylinder,  which 
is  heated  by  flues  as  in  the  case  of  the  Scottish  type  of  retort 
described  previously.  The  vapours  liberated  pass  between 
the  cast-iron  rings  into  the  centre  of  the  chamber,  whence 
they  pass  off  by  the  vapour  delivery  pipe. 

The  tars  obtained  from  the  distillation  of  such  lignites 
and  from  pyropissite  in  particular  (which  may  yield  up 
to  20  per  cent,  of  tar)  are  light  (the  specific  gravity 
varying  from  0*8406  to  0*910),  and  are  rich  in  paraffin 
wax. 

The  vast  quantities  of  peat  found  in  various  parts  of 
the  globe  will  doubtless  one  day  also  serve  as  a  basic  material 
for  the  manufacture  of  fuel  and  other  oils. 

Up  to  the  present,  however,  little  has  been  done  in  this 
direction  except  in  Germany,  the  removal  of  the  large 
percentage  of  water  found  in  all  peats  presenting  an  economic 
difficulty.  The  nature  of  the  oil  obtained  depends  on  the 
nature  of  the  peat  and  on  the  method  of  distillation.  Peat 
oils  mainly  composed  of  saturated  hydrocarbons  have  been 
described,  also  others  composed  largely  of  unsaturated. 

Peat  tars  contain  tar  acids  in  large  quantities,  usually 


VARIOUS   TARS  129 

also  paraffin  wax,  and  yield  a  useful  soft  pitch  as  distillation 
residue  (Technical  Paper,  No.  4,  Fuel  Research  Board). 


GENERAL  REFERENCES  TO  PART   IV.,  SECTION  F. 

Berthelot,  "  La  technique  moderne  de  1'industrie  des  goudrons  de 
houille,"  Revue  de  Metallurgie,  1920,  p.  64. 

Gluud,  "  Die  Tieftemperaturverkokung  der  Steinkohle,  1921."  Knapp, 
HaUe. 

Gregorius,  "  Mineral  Waxes."    Scott,  Greenwood  and  Co. 

Greene,  "  Treatise  on  British  Mineral  Oils."     C.  Griffin  and  Co. 

Lewes,  "  Carbonization  of  Coal."     Benn  Bros. 

Scheithauer,  "  Shale  Oils  and  Tars."     Scott,  Greenwood  and  Co. 


P. 


PART  V.— NATURAL   SOLID   AND    SEMI- 
SOLID     BITUMENS     AND     ALLIED 

SUBSTANCES 

SECTION  A.— OCCUREENCE,   CHARACTERS, 
AND  PRODUCTION 

NATIVE  solid  or  semi-solid  bitumens,  pure  or  associated 
with  varying  quantities  of  mineral  matter,  are  very  widely 
distributed,  being  found  in  some  form  or  other  in  most 
countries. 

The  materials  included  under  this  head  show  great 
variation  in  character,  not  only  in  respect  to  their  admixture 
with  mineral  matter,  but  also  in  the  chemical  composition 
of  the  bituminous  matter. 

Asphaltic  substances,  practically  free  from  mineral  matter 
are  found,  and  also  asphaltic  rock,  which  may  be  a  lime- 
stone impregnated  with  quite  small  quantities  of  bituminous 
material.  They  are  found  also  in  strata  of  all  geological 
ages  from  the  Silurian  to  the  Pleistocene. 

lyittle  is  yet  known  of  the  chemistry  of  these  bodies  ; 
they  have  really  only  been  studied  from  the  point  of  view 
of  solubility  in  various  solvents,  and  of  physical  properties 
and  behaviour  when  subjected  to  distillation. 

There  is  little  doubt  that  they  are  derivatives  of 
petroleum,  formed  by  the  removal  of  the  more  volatile 
constituents  and  by  gradual  transformation  of  the  non- 
volatile fractions.  There  is  in  many  cases  definite  geological 
evidence  that  such  transformation  has  taken  place.  Their 
frequent  occurrence  in  veins  bears  out  this  view. 

In  consequence  of  their  mode  of  formation,  types 
illustrating  various  stages  in  the  transformation  exist ;  in 
fact,  a  definite  series  ranging  from  ordinary  petroleum 
residual  asphalts  such  as  are  made  by  the  concentration  of 

130 


NATURAL  ASPHALTS,  ETC.  131 

certain  crude  oils,  to  bodies  like  albertite  which  are  so 
similar  in  appearance  to  coal  as  to  have  been  mistaken  for 
such,  may  be  distinctly  traced. 

The  differentiation  of  these  bodies  into  definite  classes 
is  therefore  difficult.  However,  a  rough  subdivision  into 
asphalts  proper,  asphaltites,  and  asphaltic  pyrobitumens 
may  be  adopted. 

(a)  Asphalts   Proper. — These   melt  below  or  not  far 
above  100°  C.     They  are  more  or  less  equally  soluble,  and 
almost    entirely    so    in    carbon    tetrachloride    and    carbon 
bisulphide,  and  to  a  large  extent  also  in  petroleum  spirit  of 
sp.  gr.  0*645.     Under  this  heading  are  included  also  the 
artificial  residual  asphalts  resulting  from  the  distillation  of 
asphaltic  base  crude  oils. 

(b)  Asphaltites. — These  have  high  melting  points,   a 
higher  fixed   carbon   content,    are  less   soluble  in   carbon 
tetrachloride,    and    still    less    so    in    petroleum    spirit    of 
sp.  gr.  0-645. 

(c)  Asphaltic  Pyrobitumens.— These  are  infusible  and 
are  only  slightly  soluble  in  carbon  tetrachloride,   carbon 
bisulphide,  or  petroleum  spirit  of  sp.  gr.  0*645. 

The  asphalts  proper  are  by  far  the  most  common. 
They  are  found  often  in  a  relatively  pure  condition,  often  in 
association  with  mineral  matter,  and  often  merely  as  an 
impregnating  material. 

Relatively  pure  native  asphalts  have  been  found  in  Cuba, 
France,  Greece,  Mexico,  the  Philippine  Islands,  Siberia, 
Syria,  Venezuela,  and  in  California,  Kentucky,  and  Utah. 

Of  these  deposits  one  of  the  largest  in  the  world  is  that 
found  in  Venezuela,  known  as  the  Eermudez  asphalt  lake. 
This  covers  an  area  of  over  900  acres,  and  has  an  average 
depth  of  about  4  feet.  It  is  supplied  from  various  springs 
from  which  the  asphalt  exudes  in  a  semi-liquid  condition, 
gradually  hardening  as  it  is  exposed  to  the  air.  Similar 
deposits  are  found  on  several  of  the  islands  in  the  delta  of 
the  Orinoco,  and  at  Maracaibo.  The  asphalt  is  practically 
free  from  mineral  matter,  but  contains  much  water.  The 
water,  which  may  amount  to  as  much  as  30  per  cent.,  is  not 


132    PETROLEUM  AND  ALLIED  INDUSTRIES 

emulsified,  and  is  easily  separated  off  by  heating.     Refined 
Bermudez  asphalt  has  the  following  characteristics  : — 

Fracture        . .          . .          . .          . .  conchoidal 

I^ustre  . .          . .          . .          . .  very  bright 

vStreak  . .          black 

Specific  gravity  at  25°  C.    . .          . .  1*06  to  ro8 

Penetration  at  25°  C.          . .          . .  20  to  30 

Ductility       . .          . .          . .          . .  about  n 

Melting  point  (K.  and  S.)  . .         . .         „     58°  C. 

Fixed  carbon  . .         . .         . .  13  to  14  per  cent. 

Solubility  in  carbon  bisulphide     . .  about  95      ,, 
Solubility  in  0*645  petroleum  ether          ,,     65 
Volatile  matter  7  hours  at  163°  C.  ,,       5 

7  hours  at  204°  C.  „       9 

Elementary  Analysis — 

C          . .         . .         . .     82*9  per  cent. 

H         10-8 

S          5'9        » 

N          07 

This  asphalt  contains  a  considerable  percentage  of  hydro- 
carbons volatile  below  200°  C.,  differing  in  this  respect 
markedly  from  the  other  noted  natural  asphalt  supply, 
viz.  that  of  Trinidad. 

Its  soft  character  is  due  to  the  high  percentage  of 
malthenes  (soluble  in  0*645  petroleum  spirit). 

The  Maracaibo  asphalt  is  similar  on  the  whole  to  the 
Bermudez  product  possessing  the  following  characteristics : — 

Specific  gravity  at  25*5°  C.    . .  . .  1*062  lo  1*078 

Penetration  at  25°  C.  . .  . .  about  25 

Soluble  in  carbon  bisulphide  . .  92  to  97  per  cent. 

Soluble  in  0*645  petroleum  spirit  . .  46  to  54        „ 

Fixed  carbon  . .          . .  15  to  19        , 

Volatile  at  163°  C.,  7  hours    . .  . .  1*5  to  5*3      „ 

Melting  point    . .          . .          . .  . .  about  100°  C. 

Some  samples,  however,  contain  considerable  quantities 


CHARACTERS   OF  NATURAL  ASPHALTS    133 

of  vegetable  matter.  It  differs  from  Bermudez  (and 
Trinidad)  asphalt  in  having  a  higher  softening  point  and  a 
lower  percentage  of  malthenes  (soluble  in  0-645  petroleum 
spirit). 

A  similar  asphalt  lake  is  known  on  the  east  coast  of  the 
island  of  Sakhalin,  in  Siberia,  but  this  has  not  yet  been 
exploited. 

The  pure  asphalt  deposits  of  France,  Greece,  Syria,  and 
the  Philippine  Islands  have  not  yet  received  much  attention. 

Native  asphalts  associated  with  varying  amounts  of 
mineral  matter  are  also  common,  many  of  the  deposits  being 
worked  commercially.  Occurrences  have  been  noted  in 
Algeria,  Arabia,  Argentine,  Austria,  Canada,  Cuba,  France, 
Germany,  Greece,  Italy,  Japan,  Mesopotamia,  Mexico, 
Portugal,  Russia,  Sicily,  Spain,  Switzerland,  Syria,  Trinidad, 
and  in  the  United  States,  in  California,  Indiana,  Kentucky, 
Louisiana,  Missouri,  Oklahoma,  Texas,  and  Utah. 

Of  these  the  Trinidad  deposit  is  the  most  important. 
The  main  deposit  occurs  in  the  form  of  a  lake  of  about 
115  acres  in  extent,  estimated  to  contain  over  9,000,000 
tons  of  asphalt.  The  asphalt  is  softer  in  the  centre,  where 
it  seems  to  be  replenished  from  underground  sources.  The 
consistency  is  such  that  it  will  easily  bear  the  weight  of  a 
man,  and  it  may  be  easily  excavated  by  means  of  pickaxes 
in  the  cool  of  the  day.  It  consists  of  an  emulsion  of  asphalt, 
water,  and  finely-divided  mineral  matter.  This  latter  is  in 
such  a  fine  state  of  subdivision  that  it  does  not  separate  out 
even  after  the  melted  asphalt  has  been  kept  standing  for 
many  months.  The  crude  asphalt  is  refined  by  heating  to 
1 60°  C.  for  some  time  to  drive  off  the  water.  The  dry  (so- 
called  refined)  product  analyses  : — 

Fracture  . .         . .         . .         . ,  conchoidal 

lustre        . .         . .         . .         . .         . .  dull 

Streak       . .          . .         . .         . .         . .  black 

Specific  gravity 1*40  to  1-45 

Penetration  at  25°  C about  7 

Ductility  at  25°  C.  about  2 


134    PETROLEUM  AND  ALLIED  INDUSTRIES 

Melting  point  (K.  and  S.)       . .         . .  about  87°  C. 

Mineral  matter            „     40  per  cent. 

Solubility  in  carbon  bisulphide         . .  „      55        „ 

Solubility  in  0*645  petroleum  ether  . .  „      34        „ 

The  pure  bituminous  matter  freed  from  mineral  matter 
analyses  : — 

Melting  point  (K.  and  S.)       . .  . .  about  55°  C. 

Fixed  carbon    ..         ..         . ..  ..         ,,12 

Soluble  in  carbon  bisulphide  . .  . .  100  per  cent. 

Soluble  in  0*645  petroleum  ether  . .  about  60  per  cent. 

Elementary  Analysis — 

C  82*3  per  cent. 

H  107       „ 

S  6*2      „ 

N  0-8      „ 

As  far  back  as  1883,  35,000  tons  of  Trinidad  asphalt  were 
imported  into  the  United  States,  and  in  1892  the  Bermudez 
product  appeared  on  the  scene. 

The  production  of  asphalt  in  Trinidad  amounted  to  over 
74,000  tons  in  1918,  but  in  1913  the  amount  was  over 
230,000  tons.  Of  recent  years,  however,  the  production  of 
asphalt  from  Mexican  and  other  petroleums  has  advanced 
with  great  strides,  so  that  at  the  present  day  the  actual 
amount  of  asphalt  from  the  Trinidad  lake,  imported  into 
the  United  States,  constitutes  less  than  5  per  cent,  of  the 
total  consumption  of  that  country  (Hubbard,  Chemical  Age, 
New  York,  1921,  p.  331). 

Many  native  asphalts  are  found  in  Cuba;  the  deposits 
are  small,  but  considerable  quantities  have  been  exported. 

With  the  exception  of  the  above-mentioned  cases, 
practically  all  the  important  natural  asphalt  deposits  take 
the  form  of  a  rock  impregnated  with  varying  quantities  of 
asphalt,  often  not  more  than  5  to  10  per  cent. 

The  chief  deposits  worked  are  found  in  Ragusa,  in 
Sicily,  Seyssel  in  France,  Jammer  in  Hanover,  and  Val  de 
Travers  in  Switzerland. 


CHARACTERS  OF  NATURAL  ASPHALTS    135 

The  Ragusa  deposits,  which  yielded  about  100,000  tons  per 
annum,  vary  in  quality,  some  specimens  containing  as  much 
as  30  per  cent,  of  asphalt,  the  usual  percentage  being,  how- 
ever, about  9.  The  Seyssel  deposits  contain  about  8  per  cent., 
Val  de  Travers  about  10,  and  the  I/immer  about  14  per  cent. 

These  asphalt  rocks  find  application  particularly  for 
compressed  asphalt  pavements.  For  such  work,  the  mineral 
constituents  should  consist,  as  far  as  possible,  of  carbonates 
of  calcium  and  magnesium.  Asphalt  rocks  containing 
appreciable  quantities  of  silica  do  not  prove  so  suitable. 

Enormous  deposits  of  an  asphalt-impregnated  sand,  the 
(wrongly)  so-called  tar-sands  of  Athabasca  exist  in  Alberta. 
The  bituminous  material  from  these  sands  has  recently  been 
examined  by  Krieble  and  Seyer  (J.A.C.S.,  1921,  p.  1337). 
They  find  the  asphalt  to  make  up  from  7  to  20  per  cent,  of 
the  sand. 

It  is  soluble  in  carbon  bisulphide   . .     100  per  cent. 
„        „          petroleum  ether      . .     86*9      „ 

These  deposits  have,  however,  not  yet  been  exploited. 
The  natural  asphalt  rocks  of  the  United  States,  though 
often  used  locally,  have  not  found  favour  in  comparison  with 
artificial  mastics  made  from  petroleum  residual  asphalts. 

The  asphaltites  fall  into  three  groups  :  The  gilsonites, 
the  glance  pitches,  and  the  grahamites,  which  differ  from 
each  other  somewhat  in  fusibility  and  fixed  carbon  content, 
but  the  line  of  demarcation  is  not  distinct,  intermediate 
products  being  found. 

Gilsonite  or  uintaite  is  found  only  in  the  United  States, 
in  a  belt  in  the  Uinta  basin,  mostly  in  Utah,  occurring  in 
vertical  veins.  The  largest  of  these  veins  is  about  18  feet 
in  diameter  and  several  miles  in  length. 

About  30,000  tons  of  gilsonite  per  year  are  produced 
from  this  one  region.     It  has  the  following  properties  : — 
Fracture    . .         . .         . .          . .         . .     conchoidal 

Lustre very  bright 

Streak     '  . .         . .         . .         . .         . .     brown 

Specific  gravity  at  25°  C.  . .         . .     ro  to  n 


136    PETROLEUM  AND  ALLIED  INDUSTRIES 

Penetration  25°  C nil 

Ductility  25°  C.  nil 

Melting  point  (K.  and  S.)       . .          . .  120  to  180°  C. 

Fixed  carbon    . .          . .          . .          . .  10  to  20  per  cent. 

Soluble  in  carbon  bisulphide  . .  over  98        „ 

Soluble  in  0-645  petroleum  ether      . .  40  to  60      „ 

Sulphur  . .         . .         . .         . .  2 

A  sample  from  Syria  had  the  following  properties  : — 

Specific  gravity  at  15°  C.  . .  . .     i'ioi 

Fixed  carbon        . .          . .          . .  -.15  per  cent. 

Soluble  in  carbon  bisulphide     . .  . .     completely 

,,         tetrachloride  . .          . .  . .  ,, 

,,        0*645  petroleum  ether  . .     28*7  per  cent. 

Melting  point  (K.  and  S.)          . .  . .     132°  C. 

The  Glance  pitches  have  been  found  in  various  localities, 
e.g.  Mexico,  Barbados,  Columbia,  Egypt,  and  Palestine. 
They  resemble  gilsonite  in  many  respects,  but  have  a 
higher  specific  gravity  1*10  to  1*15,  a  black  streak  instead 
of  brown,  and  a  higher  fixed  carbon  content  ranging  from 
20  to  30  per  cent. 

The  deposits  in  Barbados  are  worked  and  the  product 
sold  under  the  name  of  Barbados  manjak.  This  has  the 
following  properties  : — 

Colour    . .          . .          . .          . .          . .  black 

Fracture  . .          . .          . .          . .  conchoidal 

lustre    . .          . .         . .          . .          . .  bright 

Streak black 

Specific  gravity  . .          . .          . .  1*10 

Melting  point    ..          ..          ..          ..  110°  C. 

Penetration  at  25°  C.  . .          . .          . .  o 

Soluble  in  carbon  bisulphide  . .          . .  over  99  per  cent. 

,,         0*645  petroleum  spirit      . .  about  27      ,, 

Fixed  carbon 25  to  30       „ 

The  occurrence  of  glance  pitch  has  recently  been  noted 
in  Australia  (North-east  Kimberley)  Times,  October  13,  1921. 


CHARACTERS   OF  ASPHALTITES  137 

The  grahamites  occur  in  many  localities,  usually  in 
small  quantities,  often  associated  with  mineral  matter. 
The  chief  deposits  occur  in  Jackfork  Valley,  Oklahoma,  in 
a  vein  20  feet  thick  and  i  mile  in  length. 

Deposits  in  Colorado,  Cuba,  and  Trinidad  are  also  worked. 

They  are  lustrous  or  semi-lustrous,  black,  with  a  fracture 
sometimes  conchoidal,  sometimes  hackly,  and  black  streak. 

Specific  gravity  at  25°  C.,          ..         ..     1*15  to  1*50. 

Fusing  point  ranges  from  180°  to  130° 
C.,  but  melting  does  not  take  place  as 
intumescing  occurs  on  further  heating 
Fixed  carbon  high          . .       ...         . .     up  to  55  per  cent. 

Solubility  in  carbon  bisulphide  over    99         „ 

„  0*645  petroleum  spirit      . .     less    than    i    per 

cent. 
Sulphur     . .         . .         . .         . .         . .     variable  up  to  8 

per  cent. 

A  soft  variety,  known  as  Trinidad  manjak,  is  also  mined 
extensively.  Its  properties  are  somewhat  similar  to  those 
of  Barbados  manjak,  but  its  specific  gravity  is  about  1*170, 
melting  point  180°  to  230°  C.,  and  fixed  carbon  31  to  35  per 
cent. 

The  asphaltic  pyrobitumens  comprise  the  elaterites, 
albertites,  wurtzilites,  impsonites,  and  the  asphaltic  pyro- 
bituminous  shales. 

These  first  four  classes  are  sometimes  found  practically 
free  from  mineral  impurity.  There  is  little  doubt  that  these 
substances  are  derived  from  crude  petroleum  and  represent 
the  last  stages  in  its  transformation.  They  differ  markedly 
from  the  previously  described  asphaltites  in  their  relative 
insolubility  in  carbon  bisulphide. 

Elaterite  has  been  found  only  at  Castleton  (Derbyshire), 
in  South  Australia,  and  Siberia  (Lake  Balkash).  It  is  of 
scientific  interest  only. 

It  has  a  brown  streak,  is  of  indianibber-like  nature,  of 
specific  gravity  0*90  to  1*05.  It  is  insoluble  in  carbon 
disulphide. 


138    PETROLEUM  AND  ALLIED  INDUSTRIES 

The  word  elaterite  is  loosely  used  in  America  in  place  of 
wurtzilite. 

Wurtzilite  is  found  only  in  Uinta  County,  Utah,  where  it 
occurs  in  veins,  as  does  gilsonite.  These  veins  are  generally 
less  than  3  feet  in  thickness,  but  may  be  a  mile  or  two  in 
length.  About  820  tons  were  produced  in  1917. 

It  is  a  hard,  lustrous  substance,  with  light-brown 
streak,  and  conchoidal  fracture.  It  can  be  cut  into  thin 
flakes  which  are  somewhat  elastic,  rather  like  mica  in  this 
respect. 

Specific  gravity    . .          . .          . .          . .     1*05  to  1*07 

Decomposes  before  fusing 

Fixed  carbon        . .         . .         . .         . .     about  10  per  cent. 

Soluble  in  carbon  bisulphide     . .          . .         „         „ 

Practically  insoluble  in   carbon  tetra- 
chloride  and  0-645  petroleum  spirits. 

Sulphur     . .         . .         . .         . .         . .     about  5  per  cent. 

It  is  an  example  of  a  thio-kerite,  composed  chiefly  of 
kerotenes. 

Albertite. — This  occurs  typically  in  Albert  County,  New 
Brunswick,  where  it  was  mined  for  many  years,  being 
falsely  regarded  as  a  coal.  Its  mode  of  occurrence,  how- 
ever, clearly  proves  that  it  is  not  a  coal,  as  it  is  found  in  a 
fissure  or  vein  cutting  across  a  series  of  asphaltic  pyro- 
bituminous  shales.  In  this  particular  case  there  is  no 
doubt  that  the  asphaltic  pyrobituminous  shales  were  formed 
by  the  impregnation  of  the  shales  by  the  same  petroleum 
which  formed  the  albertite.  Both  substances,  as  a  matter 
of  fact,  yield  the  same  distillation  products. 

Albertite  has  the  following  properties  (Abraham)  : — 

Specific  gravity  at  25°  C 1*07  to  no 

Penetration  at  25°  C.          . .         . .     nil 

Ductility       . .          . .          . .          . .     nil 

Melting  point           . .         . .         . .     intumesces  and  decom- 
poses 
Fixed  carbon  25  to  50  per  cent. 


ASPHALTIC  PYROBITUMENS  139 

Solubility  in  carbon  disulphide     . .     slight,  2  to  10  per  cent. 
„  0-645  petroleum  ether         „     up  to  2  per  cent. 

„  hot  pyridin     . .          . .     about  30  per  cent. 

Elementary  Analysis — 

C 83-4  to  87-2 

H  ...--.•      ..         . .  9 "2  to  13*2 

S  .,;•'•       ..         ..  up  to  i '2 

N  ..         »»         „.         „    3-0 

O  . .         , .         . .  about  2  per  cent. 

A  variety  called  Tasmanite  is  found  in  Tasmania. 
Other  deposits  have  been  noted  in  Cuba,  Oklahoma,  Utah, 
and  Mexico. 

Impsonite,  which  is  found  in  Arkansas  and  Oklahoma, 
is  black  and  has  a  semi-dull  lustre.  Specific  gravity  at 
25°  C.,  1*125.  ^  is  infusible  and  insoluble  in  carbon  bisul- 
phide, has  a  high  fixed  carbon  content  (up  to  80  per  cent.). 

A  variety  from  Mesopotamia  analysed  as  follows  : — 

Specific  gravity   * .         . .         . .         . .     1*231 

Melting  point infusible 

Fixed  carbon        . .         . .         . .         . .     44*8  per  cent. 

Solubility  in  carbon  disulphide. .  10*6         „ 

,,  carbon  tetrachloride         . .     nil 

„  0*645  petroleum  ether      . .     nil 

pyridin       ..         ..         ..97 

This,  apparently  the  most  advanced  stage  in  the  trans- 
formation of  petroleum,  differs  from  the  non-asphaltic 
pyrobitumins  (the  coals,  etc.)  chiefly  in  its  low  oxygen 
content. 

The  asphaltic  pyrobituminous  shales  are  distinct  from 
the  pyrobituminous  shales,  in  that  they  are  really  shales 
impregnated  with  asphaltic  pyrobitumens.  It  is  naturally 
difficult  to  differentiate  the  two  types,  as  the  asphaltic 
pyrobitumens  are  so  slightly  soluble  in  solvents.  The 
percentage  of  oxygen  in  the  asphaltic  pyrobituminous  shales 
is  low,  being  below  2  for  wurtzilite  shales  and  less  than  3 
for  albertite  shales.  For  non-asphaltic  shales  it  varies  from 


140    PETROLEUM   AND  ALLIED  INDUSTRIES 


3  to  28  (Abrahams,  "  Asphalts  and  Allied  Substances," 
p.  159).  Moreover,  on  treating  in  a  closed  retort  to  300° 
to  400°  C.  the  asphaltic  pyrobituminous  shales  will  depoly- 
merize  and  become  more  soluble  in  carbon  bisulphide ;  the 
non-asphaltic  shales  do  not  do  so. 

The  non-asphaltic  pyrobituminous  shales  have  apparently 
been  derived  from  the  decomposition  of  vegetable  matter 
in  a  manner  similar  to  that  by  which  coal  was  formed. 
These  two  types  of  substances,  moreover,  differ  in  respect 
to  the  products  yielded  by  destructive  distillation.  The 
asphalts,  asphaltites,  and  asphaltic  pyrobitumens  yield 
usually  open  chain  hydrocarbons,  the  non-asphaltic  pyro- 
bitumens, chiefly  cyclic  hydrocarbons.  The  properties  of 
the  asphalts,  asphaltites,  and  asphaltic  pyrobitumens  may 
be  most  readily  compared  by  means  of  the  following  table  : — 


Fixed 

Sol.  in 

Soluble 

Sul- 

Sp. gr. 

M.  pt. 

carbon 
%. 

0-645  pet. 
ether  %. 

inCSp 

%.2 

phur. 

Asphalt  manufactured  from  j 
Mexican  petroleums      .  .  J 

I  -06 

57°C. 

*4 

60 

100 

5 

Trinidad  lake  asphalt,  free} 
from  mineral  matter        / 

I  065 

55 

12 

63 

100 

7 

Gilsonite     .  . 

I'll 

120/180 

10/20 

40/60 

IOO 

2 

Glance  pitch 

I-I5 

I2O 

25/30 

25 

IOO 

8 

Grahamite  .  . 
Wurtzilite  .  . 

I'3     } 

I  -06 

Intumesce 
with 

55 

10 

traces 
nil 

IOO 
10 

8 
5 

Albertite     .  . 

I-I 

decompo- 

4° 

nil 

5 

i 

Impsonite  .  . 

I'2      J 

sition. 

80 

nil 

nil 

— 

The   above   figures   are   approximate   only,    being    given   merely   for 
purposes  of  comparison. 

It  will  be  realized  from  a  consideration  of  the  above 
that  the  chemical  nature  of  the  asphaltites  and  asphaltic 
pyrobitumens  is  very  far  from  being  understood.  The 
means  of  discrimination  between  the  various  classes  of  the 
series  are  inadequate  and  empirical,  many  intermediate 
varieties  being  known.  There  are  however,  undoubtedly, 
grounds  for  the  presumption  that  these  substances  are 
petroleum  derivatives  and  that  they  form  a  series  repre- 
senting stages  in  its  transformation. 


ASPHALTIC  PYROBITUMENS 


141 


Richardson  (J.  Ind.  and  Eng.  Chem.,  vol.  8,  p.  493)  gives 
data  from  the  analyses  of  a  number  of  gilsonites  and 
grahamites  which  bear  out  this  view,  and  demonstrate  that 
the  changes  which  particular  types  of  petroleum  undergo  in 
nature  depend  on  the  environment. 


Flow-point  °F. 

Sp.  gr. 

Per  cent, 
soluble  in  0*64  5 
petroleum 
spirit. 

Per  cent, 
fixed 
carbon. 

GILSONITES— 

Utah  softest 

285 

I  -01  1 

55'5 

lO'O 

»         »» 

1-037 

46-9 

I2'3 

* 

260 

— 

47-2 

12-8 

it 

345 

1-037 

46-I 

I3'9 

,,     hardest 

intumesces 

i  '05  7 

24-5 

16-7 

G  RAHAMITES  

Cuba  Bahia 

intumesces 

I-I57 

38-8 

40-0 

Trinidad 

tt 

1-156 

14-8 

40-0 

W.  Virginia 

tt 

1-130 

9*4 

36-8 

Colorado 

1-160 

0-8 

47H 

Oklahoma 

•• 

1-184 

0-4 

5IH 

The  occurrence  of  a  material  intermediate  in  character 
between  asphalt  and  gilsonite  in  the  central  valley  of 
California  at  Asphalto  further  confirms  this  idea. 

The  development  of  this  extremely  interesting  question 
will  entail  much  patient  research. 

A  considerable  industry  connected  with  the  native 
asphalts  has  developed  in  the  United  States.  In  1919  the 
production  reached  88,281  short  tons  (Cottrel,  "Asphalt 
and  Related  Bitumens,"  "Mineral  Resources  of  the  United 
States/'  1919,  p.  279).  Of  this  amount  53,589  was  rock 
asphalt,  the  balance  being  made  up  of  gilsonite,  grahamite, 
wurtzilite,  and  impsonite  (Hubbard,  Chemical  Age,  New 
York,  1921,  p.  331). 


GENERAL  REFERENCES  TO   PART  V.,   SECTION   A. 

Abraham,  "  Asphalts  and  Allied  Substances."     D.  van  Nostrand  Co. 
Danby,  "  Natural  Rock  Asphalts  and  Bitumens."     Constable  and  Co. 
Ladoo,  "  The    Natural  Hydrocarbons,"      Reports  on  Investigations, 
U.S.  Bureau  of  Mines,  1920. 

Peckham,  "  Solid  Bitumens."     Myrom  Clark  Pub.  Co. 
Richardson,  "  The  Modern  Asphalt  Pavement."     Wiley  and  Sons. 


SECTION  B.— APPLICATIONS 

THK  applications  of  the  natural  solid  and  semi-solid  bitumens 
are  many  and  varied.  Enormous  quantities  of  the  rock 
asphalts  and  asphalts  proper  are  used  for  road-making  or 
paving  purposes,  smaller  quantities  of  the  asphaltites  are 
used  for  many  special  purposes,  while  some  of  the  natural 
pyrobitumens  are  little  used.  Of  the  mining  of  these 
materials  little  need  be  said. 

The  rock  asphalts  are  quarried  according  to  usual 
methods.  They  are  largely  used  for  surfacing  roads  which 
are  required  to  stand  very  heavy  traffic.  The  broken  pieces 
of  rock  asphalt  as  received  from  the  mine,  are  passed 
through  disintegrators  and  reduced  to  a  fine  powder,  which 
forms  the  basis  of  the  made-up  products.  The  rock  from 
the  quarries  may  contain  various  percentages  of  asphalt 
and  so  usually  requires  blending  with  either  mineral  matter 
or  asphalt  to  obtain  a  mixture  containing  the  requisite 
proportion  of  asphalt.  In  many  cases  a  powdered  rock 
asphalt  rich  in  asphalt,  is  blended  with  one  poor  in  asphalt 
to  obtain  the  desired  result.  In  other  cases  the  powder  is 
incorporated  with  petroleum  asphalt,  heated,  cooled,  and 
again  disintegrated.  The  asphalt  is  first  melted  in  a  special 
mixer  and  the  powdered  rock  is  added  and  thoroughly 
incorporated  at  a  temperature  of  200°  C.  It  is  then  run  off 
into  moulds  arranged  on  a  concrete  floor  and  allowed  to  cool. 
The  floor  and  sides  of  the  moulds  are  previously  coated  with 
whiting  or  other  material  to  prevent  the  adhering  of  the 
asphalt.  In  some  cases  coal-tar  products,  or  shale-oil 
products  are  used  in  place  of  asphalt,  but  the  resulting 
product  is  unsatisfactory.  This  rock  asphalt  is  applied  to 
road  surfaces  by  the  compressed  powder  method.  A  good 

142 


APPLICATIONS  OF  NATURAL  ASPHALTS,  ETC.    143 

concrete  foundation  is  essential.  The  powder  must  be  laid 
down  on  a  dry  surface  in  dry  weather.  The  powder  is 
heated  to  a  temperature  varying  from  100°  to  150°  C., 
spread  out  on  the  surface  of  the  concrete,  raked  to  the 
necessary  thickness,  and  then  compressed  by  tamping  with 
heated  rammers,  the  surface  being  finally  smoothed  off  by 
heated  irons.  As  a  decrease  of  volume  of  the  heated  powder, 
to  the  extent  of  40  per  cent,  takes  place  on  compression,  allow- 
ance for  this  must  be  made  when  laying  down  the  powder. 

This  method  of  road-making  is  to  some  extent  being 
superseded  by  rock  asphalt  tiling.  Tiles  of  about  a  square 
foot  in  area  are  made  in  the  factory,  being  subjected  to 
compression  in  hydraulic  presses.  A  more  uniform  and 
denser  material  is  thus  assured.  The  tiles  are  easily  laid, 
the  edges  being  sealed  by  dipping  in  melted  asphalt. 

A  rock  asphalt  surface  stands  up  very  well  to  heavy 
vehicular  traffic,  the  constant  heavy  pressure  keeping  the 
material  in  good  condition.  The  natural  asphalts  of  Trinidad 
and  Berrnudez  are  also  largely  used  for  road  work.  In  the 
case  of  the  Trinidad  lake  the  crude  asphalt  is  obtained  by  a 
quarrying  process,  as  the  asphalt  is  sufficiently  hard  to 
allow  of  its  being  broken  up  by  pickaxes,  except  in  the 
hottest  part  of  the  day.  A  movable  decauville  track  is  laid 
down  on  sleepers  on  the  surface  of  the  lake,  the  surface 
being  sufficiently  hard  to  allow  of  this  temporarily. 

The  asphalt  as  mined  from  the  Trinidad  lake  contains 
about  50  per  cent,  of  its  bulk  of  water,  decaj^ed  wood,  and 
vegetable  matter.  The  impure  product  is  heated  for  some 
hours  in  large  cauldrons,  the  temperature  being  finally 
raised  to  160°  C.  The  vegetable  refuse  which  floats  to  the 
top  is  skimmed  off,  and  the  molten  asphalt  is  then  drawn 
off  leaving  the  excess  of  solid  mineral  matter  at  the  bottom 
of  the  cauldron.  The  so  made  "  Trinidad  epure  "  is  then, 
however,  far  from  pure.  vSuch  a  crude  method  of  refining 
undoubtedly  harms  the  product,  as  the  portions  of  the 
asphalt  near  the  sides  of  the  cauldron  must  often  be  over- 
heated. The  material  is  more  satisfactorily  treated  by 
superheated  steam,  avoiding  the  use  of  direct  fires.  Trinidad 


144    PETROLEUM  AND  ALLIED  INDUSTRIES 

asphalt  cannot,  however,  be  purified  completely  in  this  way. 
About  35  per  cent,  of  exceedingly  finely  divided  mineral 
matter  is  obstinately  retained  emulsified  in  the  asphalt. 
The  marketed  product  always  contains  this  mineral  matter. 
The  pure  bituminous  material  could  only  be  obtained  by 
means  of  extraction  by  solvents.  This  is,  however,  un- 
necessary as  the  bulk  of  the  Trinidad  asphalt  is  used  for 
road-making,  for  which  purpose  it  must  in  any  case  be 
mixed  with  mineral  "  fillers."  The  water  and  mineral 
matter  associated  with  Bermudez  asphalt  separates  out 
much  more  easily. 

By  far  the  most  important  application  of  the  Trinidad 
and  Bermudez  asphalts  is  that  of  road-making.  For  the 
same  purpose,  too,  the  asphalts  made  from  certain  crude 
petroleums,  notably  those  of  Mexico,  are  used  to  a  very 
great  extent,  and  the  application  for  road-making  purposes 
of  both  types  may  well  be  considered  together. 

The  asphalts  made  from  crude  oil  possess  one  great 
advantage  in  that  they  can  be  made  of  any  desired  con- 
sistency simply  by  varying  the  extent  to  which  the  crude 
oil  is  concentrated  down  in  the  process  of  manufacture. 

The  naturally  occurring  asphalts  are  more  or  less  of 
constant  composition,  too  hard  for  certain  classes  of  work. 
They  therefore  require  to  be  "  cut-back  "  or  ' 'fluxed  "  with 
less  viscous  oils  in  order  to  give  products  of  the  required 
consistency. 

The  consistency  of  an  asphalt  for  road-making  purposes 
may  be  judged  by  the  "  penetrometer."  This  is  an  instru- 
ment which  records  in  tenths  of  a  millimetre  the  distance  to 
which  a  standard  No.  2  sewing  needle,  loaded  with  a  weight 
of  100  grams,  will  sink  into  the  asphalt  at  a  temperature  of 
77°  F.  (25°  C.)  in  five  seconds.  This  is  known  as  the 
"  penetration." 

The  types  of  asphalts  used  for  road  work  have  penetra- 
tions varying  from  40  to  200,  according  to  the  class  of  work. 
The  penetration  of  Trinidad  lake  asphalt  is  only  about  7 
owing  to  the  high  content  of  mineral  matter,  that  of  the 
Bermudez  product  being  about  25. 


APPLICATIONS  OF  NATURAL  ASPHALTS,  ETC.   145 

Apart  from  "  compressed  asphalt  paving  "  as  described 
above,  there  are,  broadly  speaking,  three  systems  of  road 
construction  involving  the  use  of  asphalt. 

They  are  :  (i)  Asphalt  carpet ;  (2)  Asphalt  macadam  ; 
(3)  Grouting  or  penetration  work. 

For  asphalt  carpeting  work  the  asphalt  is  mixed  with 
definite  proportions  of  sand,  stone  (or  clinkers,  etc.)  and 
filler,  all  carefully  graded  to  specification.  The  mixture  is 
spread  hot  on  the  road  and  carefully  rolled.  Such  carpets 
may  be  laid  down  on  cement  or  on  a  previously  existing 
macadam  surface. 

In  many  cases  two-coat  work  may  be  carried  out,  a 
sub-coat  of  3  inches  or  more  of  a  coarse  asphaltic  concrete 
being  laid  down  and  consolidated,  a  i-J-inch  carpet,  made 
of  more  finely  graded  material  being  laid  down  on  top.  The 
material  used  should  be  graded  so  that  a  voidless  matrix 
may  be  obtained. 

For  asphalt  macadam  work  the  macadam  is  heated  in  a 
mixer  with  sufficient  asphalt  to  coat  the  aggregate  completely. 
The  mixture  is  then  carted  into  position  while  still  warm, 
laid  down  and  rolled. 

For  grouting  or  penetration  work  an  asphalt  of  softer 
quality  may  be  used.  The  aggregate  suitably  graded  is 
laid  down  and  rolled  and  the  hot  asphalt  is  poured  over,  or 
sprayed  on  by  a  special  machine,  at  the  rate  of  about 
ij  gallons  to  the  square  yard.  The  surface  is  then  lightly 
covered  with  dry  chippings  and  the  road  is  then  well  rolled. 
A  sealing  coat  of  asphalt  is  then  applied  and  a  final  dressing 
of  chippings.  Dryness  is  essential  to  the  making  of  a  good 
asphalt  road. 

As  a  road  binder  petroleum  asphalt  is  superior  to  coal 
tar  in  many  respects.  For  example,  coal  tar  contains 
water  soluble  constituents,  also  volatile  constituents  such  as 
naphthalene.  Moreover,  it  is  difficult  to  obtain  coal  tar  of 
uniform  composition,  and  the  gradual  introduction  of  vertical 
retorts  and  of  carbonization  at  lower  temperatures  is  bring- 
ing about  the  production  of  tars  less  suitable  for  road  work 
than  those  produced  by  carbonization  in  horizontal  retorts, 
p.  10 


146    PETROLEUM  AND  ALLIED  INDUSTRIES 

The  subject  of  road-making  is,  however,  beyond  the 
scope  of  this  work,  so  for  further  details  the  reader  must  be 
referred  to  any  of  the  many  books  now  published  dealing 
with  this  subject. 

The  other  uses  of  natural  asphalts  will  be  described  in 
the  section  dealing  with  petroleum  asphalts. 

The  natural  asphaltites  which  occur  in  veins  are  generally 
mined  by  crude  methods.  The  largest  known  vein  of 
grahamite,  namely  that  at  Jackford  Creek,  in  Oklahoma, 
where  the  asphaltite  fills  a  fault  in  sandstone,  is  mined  by 
means  of  inclined  shafts,  in  a  manner  similar  to  that  used 
in  Scotland  for  shales. 

The  natural  asphaltites  are  often  employed  just  as 
mined.  Should,  however,  they  be  mixed  with  adhering 
mineral  matter,  they  may  be  refined  by  merely  melting  off. 

Gilsonite  is  used  principally  in  the  manufacture  of 
paints,  japans,  and  varnishes.  Its  value  in  this  respect  is 
enhanced  by  the  fact  that  it  is  easily  miscible  with  fatty 
acid  pitches  (grahamite  is  not) . 

Such  bituminous  paints  are  made  from  a  variety  of 
substances  such  as  natural  asphaltites,  petroleum  asphalts, 
blown  asphalts,  various  tars  and  pitches,  montan  wax, 
fatty  oils  and  acids,  and  various  resins,  together  with 
various  mineral  fillers,  incorporated  with  various  solvents 
such  as  benzine,  kerosene,  turpentine,  resin  oils,  coal-tar 
products,  carbon  tetrachloride,  alcohols,  acetones,  etc. 
Gilsonite  is  also  largely  used  in  the  rubber  industry  for 
incorporation  into  motor-car  tyres,  as  a  vulcanized  mixture 
of  rubber  and  gilsonite  is  much  more  resistant  to  oxidation 
and  changes  of  temperature  than  is  rubber  alone. 

Grahamite  is  also  used  in  the  manufacture  of  varnishes, 
rubber  substitutes,  insulating  material,  as  is  also  manjak. 

Wurtzilite  is  used  for  the  manufacture  of  the  so-called 
wurtzilite  asphalt  or  pitch,  commercially  known  as  "  kapak." 
This  is  made  by  heating  wurtzilite  to  about  300°  C.  under 
pressure.  Decomposition  sets  in  and  oils  are  evolved  which 
are  condensed  and  returned  to  the  vessel.  The  mass  is  thus 
converted  into  a  fusible  substance  differing  from  the  original 


APPLICATIONS  OF  NATURAL  ASPHALTS,  ETC.   147 

wurtzilite  in  being  soluble  in  carbon  bisulphide  and  0-645 
petroleum  spirit.  This  kapak  is  used  for  manufacture  of 
varnishes,  insulating  material,  and  for  weatherproof  coatings, 
etc. 


GENERAL  REFERENCES  TO  PART  V.,   SECTION   B. 

Baker,  "  Roads  and  Pavements."     J.  Wiley  and  Son. 

Blanchard,  "  American  Highway  Engineers  Handbook."  J.  Wiley  and 
Son. 

Boulnois,  "  Modern  Roads."     Arnold. 

Hubbard,  "  Dust  Preventives  and  Road  Binders."     J.  Wiley  and  Son. 

Kohler  und  Graefe,  "  Natiirliche  und  Kiinstliche  Asphalte."  Vieweg 
und  Sohn. 

Tillson,  "  Street  Pavements  and  Paving  Materials."     J.  Wiley  and  Son. 


PART  VI.— THE   NATURAL  MINERAL 
WAXES 

UNDER  this  heading  may  be  described  the  two  substances 
ozokerite  and  montan  wax,  the  former  of  which  is  found 
native,  the  latter  extracted  from  certain  lignites  by  a  solvent. 
These  two  substances  differ  fundamentally  in  character, 
both  from  each  other  and  from  the  asphaltic  substances 
dealt  with  in  the  last  part. 

Ozokerite  is  a  naturally  occurring  hydrocarbon  sub- 
stance. It  is  known  also  as  mineral  wax,  rock  tallow, 
mineral  adipocere,  citricite  (in  Moldavia),  nestegil  (Caspian 
area),  and  baikerite  (Siberia). 

It  is  composed  of  hydrocarbons  of  higher  melting  point 
than  those  constituting  the  paraffin  waxes.  It  is  usually 
found  associated  with  petroleum  and  often  contains  an 
admixture  of  paraffin  wax,  in  which  cases  the  melting  point 
is  lower.  Such  mixtures,  intermediate  in  character  between 
pure  ozokerite  and  paraffin  wax,  are  known  as  "  kindebal." 

It  is  usually  found  in  fissures  or  veins,  irregular  in 
character.  It  has  in  all  probability  entered  these  veins 
from  below,  and  is  a  derivative  of  paraffinaceous  petroleum. 
A  product  known  as  rod-wax,  often  found  clogging  up  the 
pumps  in  paraffin  wax-base  oil  wells,  is  similar  to  ozokerite 
in  nature. 

It  is  found  chiefly  in  Galicia,  the  largest  deposits  being 
in  the  Boryslaw  area ;  also  in  Moldavia  (Rumania),  and  in 
Cheleken  in  the  Caspian  Sea  (Petroleum  World,  1917, 
p.  136). 

In  the  United  States  it  has  been  found  in  Utah  (Higgins, 
Salt  Lake  Min.  Rev.,  1916,  p.  17).  It  is  a  waxy  substance 
varying  in  colour  from  yellow  through  brown  to  black, 
according  to  the  impurities  present.  It  varies  in  con- 

148 


THE  NATURAL  MINERAL   WAXES         149 

sistency,  sometimes  having  a  conchoidal  fracture,  sometimes 
being  quite  soft.  Its  specific  gravity  varies  from  0*85  to 
i -oo,  melting  point  from  60  to  90°  C.  Its  fixed  carbon 
value  ranges  up  to  10  per  cent.  If  pure  it  is  completely 
soluble  in  carbon  bisulphide  and  in  0*645  petroleum  ether. 
The  elementary  analysis  of  the  purified  hydrocarbon  product 
is  C.  85  per  cent.,  H.  15  per  cent.  It  can  be  distilled  in  high 
vacuum  without  decomposition,  but  at  ordinary  pressures 
it  decomposes  yielding  oils,  paraffin  wax,  and  an  asphaltic 
residue.  The  total  output  does  not  amount  to  more  than  a 
few  hundred  tons  per  year. 

Ozokerit  is  mined  by  the  normal  methods  applicable  to 
any  such  substance,  a  mixture  of  ozokerit  and  gangue  or 
associated  mineral  contamination  being  raised  to  the  surface. 
The  mixture  is  then  separated  by  hand  picking.  Those 
portions  which  consist  of  lumps  of  rock  with  small  quantities 
of  ozokerit  adhering  or  enclosed  are  boiled  up  with  water, 
and  the  wax  which  rises  to  the  surface  is  separated  off. 

The  wax  so  obtained,  together  with  the  picked  wax,  is 
then  melted,  care  being  taken  to  keep  the  temperature  as 
low  as  possible,  the  molten  wax  free  from  mineral  impurities 
being  drawn  off  from  the  surface  and  cast  into  moulds. 

Ozokerit  is  usually  refined,  the  resulting  product  being 
termed  Ceresin. 

The  dried  and  melted  ozokerit  is  heated  with  a  few 
per  cent,  of  fuming  sulphuric  acid,  with  adequate  mixing, 
at  a  temperature  of  about  120°  C.,  the  process  being  repeated 
as  often  as  necessary  in  order  to  obtain  a  colourless 
product,  a  considerable  quantity  of  acid  tar  being  formed. 
Alternately,  instead  of  allowing  the  acid  tar  to  settle,  the 
whole  mass  is  heated  up  to  from  160°  to  200°  C.  An 
energetic  oxidation  sets  in,  with  copious  evolution  of  sulphur 
dioxide.  The  temperature  is  maintained  at  200°  C.  until 
all  the  free  acid  has  been  expelled.  If  a  little  free  acid  still 
remain  this  may  be  neutralized  by  an  alkaline  fuller's-earth 
added  in  the  air-dry  condition  to  the  ceresin  at  a  temperature 
of  about  150°  C.  After  settling  the  wax  is  drawn  off  and 
treated  with  a  decolorizing  powder,  the  carbonaceous  residue 


150    PETROLEUM  AND  ALLIED  INDUSTRIES 

from  the  manufacture  of  ferrocyanides  being  usually  used. 
Separation  of  the  wax  from  the  decolorizing  powder  is 
effected  by  filter  pressing. 

The  refined  ozokerit  or  ceresin  is  amorphous  in  character, 
resembling  beeswax  in  character.  Its  specific  gravity  is 
about  0*920.  Melting  point  60  to  90°  C.  Owing  to  its  high 
melting  point  and  its  miscibility  with  vegetable  and  animal 
fats  and  oils  it  is  a  valuable  product,  commanding  a  much 
higher  price  than  does  paraffin  wax,  with  which  it  is  conse- 
quently often  adulterated.  The  question  of  the  identification 
of  paraffin  wax  in  ceresin  is  therefore  of  importance. 

As  mixtures  of  ceresin  and  paraffin  have  no  well-defined 
melting  point,  a  series  of  fractions  may  be  obtained  by 
carefully  cooling  the  mixture.  The  examination  of  the 
melting  points  of  these  fractions  will  disclose  the  presence 
of  paraffin  (Berlinerblau,  "  Das  Erdwachs,"  1897,  p.  195). 
The  other  adulterants,  e.g.  saponifiable  fats,  resins,  etc.,  are 
more  easily  detected,  as  the  determination  of  the  saponifi- 
cation  value  will  at  once  indicate  their  presence.  For  details 
of  these  methods  reference  should  be  made  to  one  of  the 
standard  works  such  as  Holde,  "  Examination  of  Hydro- 
carbon Oils,  etc." 

Ceresin  is  largely  used  for  making  candles,  its  hardness 
and  high  melting  point  rendering  it  superior  to  paraffin  in 
this  respect.  It  is  largely  used  in  the  manufacture  of 
polishes,  waterproofing,  and  insulating  materials,  of  sealing 
waxes,  leather- treating  greases,  and  so  forth ;  also  as  a  basis 
for  pomades  and  ointments,  and  for  modelling  waxes, 
gramophone  records,  and  many  such  kindred  uses. 

Montan  Wax. — A  product  of  an  entirely  different 
nature  which  may  be  described  here  is  that  known  as 
"  Montan  wax."  This  interesting  substance  is  obtained  from 
certain  Thuringian  and  Bohemian  lignites,  and  the  peculiar 
lignite  known  as  pyropissite.  These  lignites  by  extraction 
with  solvents  such  as  benzol  yield  montan  wax  ;  on  distilla- 
tion in  the  usual  manner  they  yield  oils  rich  in  paraffin 
wax  (p.  127).  Pyropissite  as  brought  to  the  surface  is  a 
lightish  yellow,  earthy-looking  substance,  containing  much 


THE  NATURAL   MINERAL   WAXES         151 

water,  which,  however,  readily  dries  off  on  exposure  to  the 
air.  Supplies  of  this  mineral  are  now  however  rapidly 
nearing  exhaustion. 

If  pyropissite  be  extracted  with  various  solvents  a 
bituminous  product  similar  to  ozokerite  in  appearance  is 
obtained,  the  nature  dependent  to  some  extent  on  the 
solvent  used.  This  bituminous  product,  however,  is  very 
difficult  to  refine  to  a  white  product,  except  by  using  more 
than  an  equal  weight  of  oleum,  followed  by  decolorizing 
powder  and  subsequent  extraction  of  the  mass  by  benzine. 
Boy  en  found  that  this  bituminous  product  could  be  distilled 
with  steam,  yielding  a  pale  yellowish,  crystalline  body  with 
a  high  melting  point  (over  70°  C.).  This  method  forms  the 
basis  of  the  manufacturing  process  now  adopted.  The  raw 
bituminous  material  which  is  the  starting  point  for  the 
manufacture  of  montan  wax,  is  obtained  from  the  lignite 
either  by  extraction  or  by  distillation  in  presence  of  much 
superheated  steam  in  cylindrical  retorts.  The  distillate  so 
obtained  differs  from  the  distillate  obtained  by  distilling  at 
higher  temperatures  with  less  steam,  the  latter  containing 
much  paraffin  wax. 

This  bituminous  product,  or  the  product  obtained  by 
extraction  of  the  liquid  with  benzol,  is  then  subjected  to 
several  distillations  in  vacuo  with  the  aid  of  superheated 
steam.  The  mineral  wax  so  obtained  is  subsequently 
refined  in  a  normal  way,  by  treating  it  in  benzol  solution 
with  decolorizing  powders,  the  benzol  being  subsequently 
distilled  off.  The  montan  wax  so  obtained  is  a  faintly 
yellow-tinted,  hard  crystalline  substance,  somewhat  like 
stearin  in  appearance,  possessing  a  faint,  pleasant,  aromatic 
odour.  The  specific  gravity  varies  from  0*9  to  1*0  ;  the 
melting  point  from  80°  to  90°  C.  It  contains  82  to  83-5  per 
cent,  carbon,  14  to  14-5  per  cent,  hydrogen,  3  to  6  per  cent, 
oxygen,  and  traces  of  sulphur  and  nitrogen  (Marcusson, 
Chem.  Rev.  Fett-Harz.  Ind.t  1908,  p.  143). 

Montan  wax  differs  fundamentally  from  paraffin  wax  in 
that  it  is  composed  of  a  mixture  of  an  acid  (montanic)  of 
high  molecular  weight,  with  esters  of  an  alcohol  of  high 


152    PETROLEUM  AND  ALLIED  INDUSTRIES 

molecular  weight.  This  montanic  acid  has  a  melting  point 
of  83°  to  84°  C.  Tetracosanol,  ceryl  alcohol,  and  myricyl 
alcohol  have  been  identified  in  montan  wax  by  Pschorr  and 
Pfaff  (Ber.,  1920,  p.  2147) .  Montan  wax  is  used  in  admixture 
with  paraffin  wax  for  candle-making,  in  making  substitutes 
for  the  valuable  carnauba  wax,  for  insulating  materials, 
polishes,  and  many  other  such  purposes.  Owing  to  its  high 
melting  point  as  compared  with  paraffin  wax,  it  commands 
a  higher  price. 


GENERAL  REFERENCES  TO  PART  VI. 

Berlinerblau,  "  Das  Erdwachs."     Vieweg  tmd  Sohn. 
Graeie,  "  Braunkohlenteer  Industrie."     Halle. 
Gregorius,  "  Mineral  Waxes."     Scott,  Greenwood  and  Co. 


PART  VIL— THE   WORKING   UP   OF 
CRUDE   OILS 

SECTION  A.— DISTILLATION  OF  CRUDE  OIL 

IN  few  cases  only  does  crude  petroleum  issue  from  the 
wells  in  a  condition  ready  for  marketing,  the  content  of 
volatile  fractions,  which  may  be  low,  being  usually  sufficient 
to  cause  the  flash-point  of  the  crude  to  be  below  150°  F.,  the 
value  usually  accepted  as  the  low  limit  for  commercial  fuel. 
Certain  heavy  crudes  have,  however,  flash-points  higher  than 
this  figure,  and  such  crudes  may  be  marketed  directly  as 
liquid  fuels,  provided  that  they  are  free  from  admixed  water 
and  have  not  too  high  setting  points  or  viscosities. 

In  the  majority  of  cases,  however,  crude  oils  require 
treatment  in  order  to  remove  volatile  constituents,  valuable 
lubricating  oil  or  wax  fractions,  or  asphalt,  as  the  case 
may  be. 

The  actual  detailed  treatment  necessary  for  any  particular 
crude  will  depend  on  (a)  the  nature  of  the  crude,  (b)  the 
market  value  and  cost  of  extraction  of  the  various  products 
it  contains. 

The  method  of  general  application  for  the  working  up 
of  crude  oils  is  that  of  distillation  under  various  conditions, 
refrigeration,  filtration,  and  chemical  treatment  being  also 
applied  for  certain  purposes.  As  crude  oils  are  com- 
posed of  a  complex  mixture  of  substances  of  varying 
boiling  points,  a  rough  separation  only  into  fractions  of 
narrower  boiling  point  ranges  may  be  effected  by  simple 
distillation. 

Distillation  may  be  carried  out  in  various  ways,  in 
many  different  types  of  plant  and  with  very  varying 
results. 

153 


154    PETROLEUM  AND  ALLIED  INDUSTRIES 

The  methods  usually  adopted  may  be  divided  into — 

(1)  Distillation  at  atmospheric  pressure. 

(2)  ,,          under  vacuum. 
%        (3)            „          underpressure. 

It  is  superfluous  "to  explain  here  that  the  boiling  point 
of  a  liquid  depends  on  the  pressure.  As  the  constituents 
of  petroleum  of  relatively  high  boiling  points  are  unstable 
at  high  temperatures,  i.e.  begin  to  "  crack  "  or  split  up  into 
hydrocarbons  of  lower  molecular  weight,  usually  with 
separation  of  carbon  and  sometimes  hydrogen,  the  method 
of  distillation  employed  will  be  that  which  enables  the 
boiling  points  to  be  lowered  or  raised  according  as  cracking 
is  to  be  avoided  or  effected.  For  example,  the  distillation 
of  lubricating  oils,  in  which  case  the  presence  of  cracked 
products  is  undesirable,  may  be  conducted  under  vacuum, 
whereas  when  the  production  of  cracked  products,  as  motor 
spirits,  is  desired,  distillation  under  pressure  may  be  employed. 
On  account  of  its  relative  simplicity,  distillation  under 
atmospheric  pressure  is,  as  far  as  possible,  the  usual  practice. 
This  is  usually,  however,  modified  by  the  introduction  of 
live  steam  into  the  oil  during  distillation,  a  method  which 
to  some  extent  gives  the  advantages  of  distillation  under 
reduced  pressure,  owing  to  the  lowering  of  the  partial 
pressure  of  the  oil  by  the  admixture  with  steam. 

Distillation  with  steam  consequently  yields  distillates  of 
higher  flash-point,  of  better  colour,  and  of  higher  viscosity 
than  does  the  so-called  dry  distillation  of  the  same  oil. 

Further,  in  the  case  of  distilling  a  paraffin  wax  crude 
oil,  fractions  of  higher  melting  point,  but  less  easily  crystalliz- 
able,  are  obtained  than  when  distilling  without  steam. 
The  subject  of  fractional  distillation  is  fully  treated  in 
Young's  book,  "  Fractional  Distillation,"  Macmillan  and  Co. 

Methods  of  distillation  may  be  further  classified  under 
two  main  headings  :  (a)  periodic,  and  (b)  continuous. 

Periodic  methods  were  naturally  those  first  employed. 
They  are  still  largely  employed  for  certain  purposes,  particu- 
larly where  the  residue  requires  to  be  brought  carefully  to 
a  certain  specification,  and,  of  course,  in  those  cases  where 


DISTILLATION  OF  CRUDE   OIL 


155 


the  residue  is  a  solid  coke.  Continuous  methods  offer  many 
advantages  which  will  be  discussed  later  and  are  now  in 
general  use. 

Periodic  Distillation  of  Crude  Oil  at  Atmospheric 
Pressure. — Periodic  distillation  at  ordinary  pressures  is 
usually  carried  out  in  steel  stills  of  cylindrical  shape. 

These  stills  may  be  of  large  capacity,  usually  of  from 
30  to  50  tons,  but  often  much  larger.  They  are  constructed 
of  steel  plates  riveted  together,  the  bottoms,  when  possible, 
being  made  of  one  piece. 


5 


FIG.  17. — Diagrammatic  view  of  crude  oil  still. 

Each  still  is  provided  with  the  following  fittings  : — 

1.  One  or  more  domes,  to  which  are  connected 

2.  The  vapour  line. 

3.  A  trap  in  the  vapour  line  to  return  to  the  still  any 
spray  of  oil  mechanically  carried  over. 

4.  One  or  more  manholes, 

5.  A  filling  pipe. 

6.  A  draw-off  pipe,  with 

7.  Internal  valve. 

8.  A  perforated  steam  pipe. 

9.  Gauge  glasses. 

10.  Thermometer. 

11.  Vacuum  and  pressure  gauge. 


156    PETROLEUM  AND  ALLIED  INDUSTRIES 

I/arge  stills,  particularly  those  used  for  lubricating  oil 
and  asphalt  manufacture,  are  fitted  with  two  or  three  domes. 
The  vapour  line  is  usually  6  or  8  inches  diameter  for  small 
stills,  but  of  12  or  15  inches,  or  larger  for  the  larger  sizes. 
The  trap  in  the  vapour  line,  an  important  item  too  often 
omitted,  may  be  fitted  with  perforated  baffle  plates.  The 
effect  of  this  in  retaining  and  returning  to  the  still  particles 
of  black  oil  mechanically  carried  over  is  very  marked. 
Without  it  distillates  of  poorer  colour  are  obtained. 

The  draw-off  pipe  should  always  be  made  of  cast  steel. 
One  or  more  perforated  pipes  for  the  introduction  of  live 
steam  are  distributed  over  the  bottom  of  the  still,  placed 
an  inch  or  so  above  the  bottom,  with  the  perforations  pointing 
downwards  and  outwards.  One  or  more  gauge  glasses 
should  be  fitted,  which  should  preferably  be  placed  a  little 
distance  from  the  still.  Sample  cocks  may  also  be  fitted 
and  are  sometimes  used  instead  of  gauge  glasses.  Floats 
of  various  designs  are  also  often  employed  to  indicate  the 
level  of  the  oil  in  the  still.  Some  form  of  thermometer  is  a 
very  necessary  adjunct. 

Stills  are  often  fitted  with  internal  fire  tubes,  just  as  are 
Cornish  boilers,  the  heating  surface  being  thus  considerably 
increased.  Such  fire  tubes  are  usually  placed  a  little  to 
one  side  of  the  vertical  diameter  of  the  still,  in  order  to 
assist  in  the  circulation  of  the  oil,  but  such  fire-tube  stills 
cannot  be  used  for  periodic  work,  as  the  reduction  in  volume 
of  the  crude  would  cause  the  level  to  fall  below  the  top 
of  the  fire  tube.  Stills  of  elliptical  cross  section  are  also 
sometimes  employed.  The  type  and  dimensions  of  the  still 
to  be  employed  depends  to  a  large  extent  on  the  nature  of 
the  work  which  it  is  called  upon  to  do.  Obviously  a  still 
constructed  to  stand  the  conditions  necessary  for  the  distilling 
off  of  volatile  fractions,  will  not  stand  up  to  the  heavy  work 
of  distilling  down  to  a  solid  residual  coke.  Stills  for  work 
of  this  type  must  be  specially  constructed  with  heavy 
riveting,  with  bottoms  made  of  as  few  plates  as  possible, 
preferably  a  single  plate  if  the  size  of  the  still  allows  it. 

The  still  is  mounted  in  a  brickwork  setting  with  a  slight 


DISTILLATION  OF  CRUDE  OIL  157 

fall  (an  inch  or  two)  towards  the  draw-off  end.  The  setting 
is  usually  arranged  so  that  the  furnace  gases  after  passing 
along  the  bottom  of  the  still  return  along  the  sides.  Dampers 
are  arranged  so  that,  as  the  volume  of  the  oil  in  the  still 
diminishes,  the  side  flues  can  be  cut  out  and  the  furnace 
gases  passed  directly  to  the  chimney.  One  square  metre 
of  heating  surface  is  usually  allowed  for  one  ton  of  distillate 
per  24  hours. 

The  vapour  pipe  leads,  in  the  simplest  types  of  plant, 
direct  to  the  coolers,  but  as  a  general  rule  some  form  of 


FIG.  1 8. — Cast-iron  box  condenser. 

fractional  condensing  plant  is  interposed.  The  coolers  or 
condensers  consist  essentially  of  a  system  of  pipes  cooled 
by  water  in  which  the  vapours  are  condensed  and  cooled. 
The  question  of  design  of  condensers  depend  upon  various 
factors,  such  as  the  availability  of  water  supply,  and  whether 
this  is  fresh  or  salt,  the  presence  or  otherwise  of  corrosive 
vapours  in  the  oil  distillates,  and  the  question  of  economy 
and  conservation  of  heat.  The  obvious  method  of  effecting 
this  is  the  use  of  crude  oil  as  a  condensing  agent  instead  of 
water.  This  modification  is  often  employed  in  continuous 
plant,  but  as  its  application  to  periodic  plant  is  not  so  simple, 
water  condensing  is  usually  adopted. 


158    PETROLEUM  AND  ALLIED  INDUSTRIES 

The  simplest  form  of  condenser  consists  of  a  series  of 
cast-iron  pipes  of  diminishing  diameter,  placed  in  a  cast-iron 
box  (Fig.  18).  The  vapours  enter  at  the  top  and  descend, 
issuing  at  the  bottom  as  condensed  distillate. 

It  is  usual  to  attach  a  gas  vent  to  the  outflow  pipe  in 
order  to  allow  any  uncondensed  gases  to  escape. 

The  condensing  surface  necessary  depends  on  many 
conditions,  the  thickness  of  the  tubes,  temperature  of  the 
distillate  to  be  condensed,  condensing  water,  and  so  forth. 
As  the  efficiency  of  the  condenser  depends  largely  on  the 
degree  of  cleanliness  of  the  surfaces  of  the  pipes,  it  is  well 
to  allow  ample  margin.  For  light  distillates  a  cooling 
surface  of  70  square  metres  per  ton  of  distillate  per  hour 
is  usually  considered  ample. 

It  must,  however,  be  borne  in  mind  that  relatively  large 
quantities  of  steam  are  employed,  and  must  be  condensed 
during  the  distilling  over  of  the  higher  boiling-point  fractions, 
so  allowance  must  be  made  for  the  condenser  to  deal  with 
this,  although  in  the  case  of  fractions  which  are  not  volatile, 
cooling  of  the  distillates  to  atmospheric  temperature  is  not 
necessary. 

Many  other  forms  of  condenser  are  employed  in  the 
petroleum  industry,  the  steel  tubular  type,  similar  to  the 
boiler  of  a  locomotive  engine  being  very  common.  A  recent 
innovation  of  very  high  efficiency  is  the  multiwhorl  cooler. 
In  this  form  the  vapours  are  condensed  in  a  nest  of  parallel 
tubes  placed  vertically,  round  which  the  ascending  stream 
of  water  (or  crude  oil)  is  made  to  ascend  spirally  by  suitable 
baffle  plates.  The  heat  exchange  is  consequently  very  good 
and  the  efficiency  high.  The  description  of  the  many  forms 
of  condenser  in  use  is,  however,  beyond  the  scope  of  this 
book. 

When  crude  oil  is  distilled  on  the  periodic  system,  the 
following  method  of  working  is  adopted.  The  crude  oil  is 
filled  into  the  still  (to  about  two-thirds  full),  which  is  then 
gradually  heated.  A  volatile  crude  will  even  begin  to  distil 
before  its  temperature  rises  to  100°  C.  In  the  case  of  crude 
oils  which  are  thick  and  heavy  and  contain  water,  much  care 


DISTILLATION  OF  CRUDE  OIL  159 

must  be  exercised  to  avoid  the  contents  of  the  still  foaming 
over  when  100°  C.  is  passed.  Such  crudes  are,  however,  best 
distilled  by  one  of  the  continuous  methods  described  later. 

The  temperature  of  the  crude  oil  is  gradually  raised 
up  to  about  125°  C.,  and  then  small  quantities  of  steam 
(preferably  superheated)  are  admitted  by  means  of  the 
perforated  steam  coil.  The  rate  of  distillation  will  be  at 
once  increased,  and  will  continue  at  temperatures  as  much  as 
50  degrees  lower  than  if  no  steam  were  admitted.  When 
the  specific  gravity  of  the  distillate  reaches  a  certain  figure, 
which  depends  on  the  nature  of  the  crude,  and  which  has 
been  determined  by  laboratory  tests,  a  cut  is  made,  i.e.  the 
distillate  is  run  into  another  receiving  tank. 

The  first  fraction  taken  may  in  some  cases  yield  a  product 
of  boiling-point  range  (when  examined  in  an  Engler  flask) 
suitable  for  benzine  or  motor  spirit,  a  product  boiling  up  to 
say  220°  C.  The  next  distillates  will  be  a  mixture  of  benzine 
and  kerosene,  the  point  at  which  the  cut  is  made  depending 
again  on  laboratory  tests.  A  point  will  then  be  reached 
when  the  boiling-point  range  and  flash-point  of  the  fraction 
allows  this  to  go  into  the  kerosene  fraction,  and  the  distilla- 
tion will  be  continued  until  the  colour  or  boiling  points  of 
the  fractions  indicate  the  necessity  of  a  change. 

The  next  fraction  will,  in  most  cases,  be  a  gas  oil,  but 
the  higher  fractions  will  depend  on  the  nature  of  the  crude. 
At  this  point  the  distillation  is  often  stopped,  as  the  residue 
in  the  still  is  considerably  reduced  in  bulk.  This  residue  is 
run  off  through  a  cooler  into  a  separate  tank  or,  better,  filled 
direct  hot  into  another  still  for  further  distillation. 

In  the  case  of  a  paraffin-wax-containing  crude,  the 
further  distillation  carried  out  with  ample  supply  of  steam 
will  yield  wax  distillates.  When  the  wax  distillates  (which 
contain  lubricating  oil)  have  been  distilled  off,  the  residue 
may  be,  in  the  case  of  certain  crudes,  e.g.  those  of  Pennsyl- 
vania, a  steam-refined  cylinder  oil.  In  other  cases  a  wax-free 
residue  is  not  obtained,  so  that  the  distillation  may  be 
carried  on  further,  yielding  wax  tailings  and  eventually 
petroleum  coke. 


i6o    PETROLEUM  AND  ALLIED  INDUSTRIES 

In  the  case  of  asphaltic  oils  the  distillation  may  be 
carried  on  so  as  to  give  lubricating  oil  distillates  and  a 
residual  asphalt  of  varying  properties  according  to  require- 
ments. Such  a  periodic  distillation  of  crude  oil  may  also 
be  carried  out  without  the  introduction  of  steam.  In  this 
case  the  distilling  temperatures  are  higher  and  a  certain 
amount  of  decomposition  or  cracking  takes  place,  resulting 
in  a  higher  }deld  of  benzine  and  kerosene  fractions.  When 
crude  oils  are  distilled  down  to  asphalt  of  a  particular 
specification,  ample  steam  is  used  to  avoid  cracking  as  far 
as  possible,  but  when  they  are  distilled  down  to  coke,  steam 
is  not  employed,  so  that  the  distillates  obtained  may  be  thin 
and  relatively  volatile  oils. 

A  distillation  carried  out  in  a  simple  plant,  as  above 
described,  is  naturally  far  from  complete.  Well-defined 
fractions  cannot  be  obtained ;  for  example,  no  clear  cut 
between  benzine  and  kerosene  can  be  made,  a  large  inter- 
mediate fraction  being  obtained.  The  larger  these  inter- 
mediate fractions,  the  more  redistillation  is  necessary. 

In  order  to  diminish  the  yield  of  such  intermediate 
fractions,  fractional  condensers,  towers,  or  dephlegmators  as 
they  are  often  incorrectly  termed,  are  introduced  into  the 
vapour  line  before  the  condensers.  These  fractional  con- 
densers behave  to  some  extent  as  fractionating  columns. 

It  would  be  difficult  to  fit  an  efficient  form  of  fractionating 
column  to  a  periodic  crude  oil  still,  owing  to  the  large  range 
of  distillates  to  be  handled  in  one  run.  These  towers 
or  dephlegmators  are  of  more  simple  construction,  but  do 
considerably  improve  the  separation  of  the  fractions  and 
obviate  the  necessity  for  much  redistillation. 

In  some  cases  a  series  of  vertical  pipes,  the  bottom  bends 
of  which  are  connected  to  run  off  pipes  passing  through  a 
cooler  are  used.  As  the  vapours  pass  through  these  pipes, 
the  higher  boiling  portions  condense  first,  so  a  series  of 
condensates  of  increasing  volatility  are  drawn  off  from  the 
successive  vertical  pipes.  A  similar  series  of  large  diameter 
pipes  laid  horizontally  is  also  used  in  lubricating-oil  distilling 
plants. 


DISTILLATION  OF  CRUDE   OIL 


161 


Other  types,  consisting  of  vertical  cylindrical  vessels 
fitted  with  various  forms  of  baffle  plates  and  sometimes  with 
water-cooling  coils,  are  often  employed. 

An  example  from  actual  practice  will  illustrate  the 
effectiveness  of  such  an  arrangement.  A  still  fitted  with  two 
cylindrical  dephlegmators,  each  containing  a  series  of  baffle 
plates  arranged  alternately  and  fitted  with  a  small  water 
coil,  yielded  three  separate  condensates,  one  running  from 
the  bottom  of  each  dephlegmator,  the  third  running  from 
the  end  of  the  main  condenser.  Samples  of  these  three 
condensates  taken  simultaneously  gave  the  following  results 
on  distillation  in  a  standard  Bngler  flask  : — 


Percentage  boiling  up  to 

Fraction  from 

Sp.  gr. 
@i5°C. 

200°  C. 

225°C. 

250°  C. 

275°  C. 

300°  C. 

Dephlegmator  I 

0-836 

_ 

_ 

5 

21 

52 

II       .. 

0-830 

— 

5 

18 

47 

80 

Main  condenser 

0-816 

7 

24 

57 

80 

94 

These  three  condensates  show  considerable  difference 
in  properties ;  that  from  the  main  condenser  could  just  go 
into  kerosene  distillate  direct,  the  other  two  could  not  ; 
that  from  dephlegmator  II  would  be  worth  redistilling  for 
kerosene  ;  that  from  dephlegmator  I  might  not.  If  all  three 
had  been  collected  together,  the  whole  fraction  would  have 
required  redistillation. 

A  type  of  tower  largely  used  in  the  United  States  (Fig. 
19)  is  made  up  of  three  or  more  sections,  each  consisting  of 
a  series  of  tubes  A  expanded  into  tube  plates,  exposed  to 
atmospheric  cooling  ;  between  each  nest  of  tubes  is  a  closed 
chamber  which  contains  a  trough  B  which  collects  the 
condensates  from  the  tubes  and  delivers  them  to  coolers 
outside  the  tower.  The  vapours  rise  through  the  tower  and 
partially  condense,  yielding  several  condensates  of  necessarily 
increasing  volatility  as  the  vapours  pass  through  the  system, 
which  often  consists  of  several  such  towers  in  series.  The 
uncondensed  vapours  from  the  top  of  the  last  tower  pass  on 
to  a  water-cooled  condenser. 

P,  ii 


162    PETROLEUM  AND  ALLIED  INDUSTRIES 


The  condensates  from  the  towers  may,  if  necessary,  be  led 
back  to  the  still.     This  is  usual  when  distilling  certain  types 

of  oil,  when  cracking  is  necessary. 
The  actual  method  of  distilling 
a  crude  oil  depends  to  such  an 
extent  on  the  nature  of  the  crude 
and  of  the  products  desired,  that 
any  detailed  description  for  a  par- 
ticular crude  would  be  of  little 
value.  The  method  of  distillation 
settled  upon  must  be  decided  by 
careful  laboratory  analyses  of  the 
fractions  obtained.  Consideration 
of  the  boiling-point  ranges,  specific 

FIG.  I9.-Fractionating  tower.    S^itieS,  flash-points,   cold   tests, 

viscosities  and  colours  of  the  dis- 
tillates will  determine  their  distribution  into  various  frac- 
tions. The  distillates  after  cooling  are  led  by  separate 
pipes  to  the  "  tail-  or  separating-house,"  where  they  are 
collected  in  separate  compartments  of  a  special  tail-box, 
or  run  by  means  of  adjusting  valves  in  a  manifold  to 
separate  tanks. 

The  actual  control  in  the  tail-house  is  usually  effected 
by  the  determination  of  the  specific  gravity  of  the  dis- 
tillate, laboratory  determinations  having  previously  indicated 
the  properties  of  the  fractions  of  particular  specific  gravities. 
It  will  be  readily  understood  that  the  process  of  periodic 
distillation  as  above  described  cannot  be  the  most  economic 
possible.  The  plant  is  not  fully  occupied,  as  time  is  lost  in 
filling  and  emptying  the  still.  Much  heat  is  also  lost  in 
alternately  heating  and  cooling  the  brickwork  setting,  a  pro- 
cess which  does  not  tend  to  increase  its  life.  The  waste  heat 
of  the  hot  residue  cannot  be  easily  utilized  owing  to  its 
intermittent  production  ;  moreover,  one  single  plant  cannot 
be  well  designed  to  handle  such  different  distillates  as  light 
benzine  and  heavy  gas  oil  or  wax  distillate.  These  and  other 
considerations  have  brought  about  the  development  of — 
Continuous  Systems  for  Distillation. — Continuous 


DISTILLATION  OF  CRUDE  OIL 


163 


plants  can,  in  the  majority  of  cases,  do  the  work  of  periodic 
plants  in  a  more  efficient  manner. 

In  addition  to  the  considerations  mentioned  above,  the 
following  advantages  are  derived.  The  general  wear  and 
tear  on  the  plant  is  much  less  as  each  section  works  at  a 
uniform,  instead  of  a  varying,  temperature.  The  capital 
expenditure  for  a  given  throughput  is  much  less  as  fewer 
stills  are  required  ;  the  fuel  consumption  is  less  and  operating 
wages  are  lower.  Moreover,  a  continuous  system  lends 
itself  much  more  easily  to  economical  utilization  of  the 
latent  heat  of  condensation  of  the  vapours  and  the  specific 
heat  of  the  residues. 

A  simple  continuous  distillation  plant  consists  of  a 
number  of  stills,  usually  from  five  to  twelve,  arranged 
cascade  faslu'on  in  a  bench  or  battery,  with  a  difference  of 
level  of  from  six  inches  to  a  foot  between  successive  stills, 
each  still  being  fitted  with  condensing  arrangements.  The 
crude  oil  is  admitted  to  the  first  still,  whence  it  flows  into  the 
second,  thence  to  the  third  and  so  on  through  the  whole 
series,  losing  a  certain  percentage  of  distillate  at  each  still, 
and  eventually  issuing  as  residue  from  the  last. 

The  arrangement  of  piping  is  simple,  as  will  be  seen 
from  the  diagram  (Fig.  20). 


FIG.  20. — Arrangement  of  continuous  stills. 


164    PETROLEUM  AND  ALLIED  INDUSTRIES 

The  crude  oil  enters  the  bench  at  A,  flows  into  the 
first  still  by  the  inlet  pipe  C,  extending  to  the  far  end  of 
the  still,  flows  out  by  the  outlet  pipe  D  into  the  next  still, 
and  so  on.  The  residue  finally  flows  out  at  B.  Each  still  is 
provided  with  a  by-pass  valve  E,  so  that  any  one  still  can 
be  cut  out  of  the  bench  for  cleaning  or  repairs.  Each  still 
is  fitted  with  its  separate  condenser,  and  in  the  better  plants, 
one  or  more  "dephlegmators"  or  fractional  condensers  are 
fitted  in  the  vapour  lines,  so  that  from  each  still  several 
separate  distillates  may  be  obtained. 

The  system  is  regulated  so  that  each  still  is  kept  at 
a  constant  temperature  and  yields  a  vapour  of  constant 
composition,  giving  a  distillate  (or  series  of  distillates)  of 
constant  composition. 

The  working  temperature  for  each  still  depends  upon  the 
number  of  stills  in  the  bench,  and  on  the  nature  of  the 
crude,  as  it  must  be  arranged  that  each  still  does  approxi- 
mately the  same  amount  of  work. 

The  table  on  next  page  shows  the  Engler  distillation 
tests  of  a  series  of  distillates  from  a  continuous  bench  and 
illustrates  how  these  distillates  vary  in  composition,  and  how 
they  may  be  grouped  together.  In  this  case  each  still  was 
fitted  with  two  dephlegmators  or  air  condensers,  each  of 
which  yielded  a  distillate,  while  a  third  distillate,  which 
passed  through  the  dephlegmators  without  condensation, 
was  condensed  in  a  separate  condenser.  These  three 
distillates  are  designated  Di,  D2,  D3  respectively. 

Distillate  iD2,  iD3,  2D2,  2D3  could  be  collected 
together  as  "  straight-run  benzine  distillate  "  ;  2Di,  3Di, 
3D2,  3D3,  4^2,  403,  503  together  as  "  benzine-kerosene 
distillate  for  redistillation  " ;  6Di,  702,  and  perhaps  8D3, 
might  be  collected  for  redistillation  into  kerosene  and 
gas  oil. 

In  continuous  systems  of  distillation  use  may  be  made  of 
the  heat  of  the  outflowing  residue,  the  temperature  of  which 
may  be  over  300 °  C.  This  residue  must  in  any  case  be  cooled, 
so  its  available  heat  can  be  economically  used  for  preheating 
the  ingoing  crude  oil  before  entering  the  first  still  of  the 


DISTILLATION  OF  CRUDE  OIL 


165 


bench.  This  is  effected  by  means  of  "heat  exchangers/' 
many  types  of  which  are  in  use.  The  most  efficient 
type  is  the  tubular.  This  is  constructed  like  a  tubular 
condenser,  but  is  usually  placed  in  a  horizontal  position 
(Fig.  21,  p.  166). 


Still  no. 

Distillate. 

Sp.  gr. 
@i5°C. 

Percentage  of  distillate  boiling  up  to 

ioo°C. 

i5o°C. 

200°  C. 

25o°C. 

300°  C. 

Flash  pt. 

I 
2 

Di 

D2 

E>3 

0732 
0726 

30 
48 

no 
90 
93 

conde 
all 
all 

nsatio 

n 

ord.  temp. 
a       a 

Di 

D2 

D3 

0770 
0765 
0-750 

I 
12 
2O 

54 
65 
75 

93 
97 
all 

all 
all 

— 

• 

3 

Di 

D2 

D3 

0-785 
0-777 
0-765 

5 

<t 

58 

80 
88 
95 

all 
all 

all 

— 

' 

4 

Di 

D2 

D3 

0-815 
0-807 
0-785 

I 

3 

10 

30 

50 
65 
75 

79 
92 

all 

all 
all 

40°  C. 

30°  c. 

ord.  temp. 

S 

Di 

D2 

D3 

0-825 
0-816 
0-800 

— 

3 
15 

32 
5° 
70 

70 
80 
90 

97 
all 
all 

42°  C. 

££ 

6 

Di 

D2 

Da 

0-840 
0-831 
0-818 

—  • 

i 

8 
20 
42 

38 
50 
75 

85 
93 
98 

46°  C. 
43°  C. 
37°  C. 

7 

DI 

D2 

r>3 

0-854 
0-844 
0-829 

— 

— 

I 

20 

10 

3° 
48 

60 
82 
90 

— 

8 

DI 

D2 

I>3 

0-866 

0-855 
0-847 

— 

con 

tains 

wax 

12 

65 

— 

The  cold  crude  oil  enters  at  C,  and  after  being  heated  by 
the  hot  residue  flowing  counter-current  from  A  to  B,  emerges 
hot  at  D.  In  the  case  of  cnide  oils  which  contain  a  large 
percentage  of  residue,  the  quantity  of  heat  disengaged  may  be 
so  great  as  to  allow  even  of  a  little  distillation  taking  place 
in  the  heat  exchanger,  which  may  then  be  fitted  with  a 


166    PETROLEUM  AND  ALLIED  INDUSTRIES 

dome  vapour  pipe  and  condenser,  and  thus  function  as  a 
still. 

Although  such   a   continuous  bench  is   an  undoubted 
improvement  on  a  battery  of  periodic  stills,  it  is,  however, 


£ 


FIG.  21. — Tubular  heat  exchanger. 

far '  from  efficient,  the  efficiency  indeed  rarely  exceeding 
35  or  40  per  cent.  This  efficiency  can,  however,  be  improved 
in  various  ways,  e.g.  by  utilizing  the  latent  heat  of  the  vapours 
for  heating  and  even  partly  distilling  the  incoming  crude, 


FIG.  22. — Distillate-crude  oil  preheater. 


and  by  inserting  heat  exchangers  or  economizers  in  the  flue 
gases.  Many  modern  continuous  benches  are  fitted  with  a 
series  of  distillate  preheaters  (Fig.  22).  These  preheaters  are 
practically  stills  heated  by  internally  placed  coils  through 


DISTILLATION  OF   CRUDE  OIL 


167 


which  the  vapours  from  the  main  stills  are  passed,  these 
vapours  being  therein  completely  or  partially  condensed. 

The  vapours  from  the  main  stills  enter  the  distillate 
preheater  at  A  and  are  partially  condensed  in  passing 
through  the  nests  of  tubes  B,  thereby  heating  the  contents 
of  the  preheater.  The  condensed  vapours  pass  off  by  the 
lower  pipe  D  to  their  coolers,  the  vapours  which  have 
escaped  condensation  passing  on  by  the  pipe  C  to  further 
water-cooled  condensers.  Each  preheater  is  connected  up 
with  inlet  and  outlet  pipes  just  as  is  a  continuous  still. 

Figure  23  illustrates  the  principle  of  such  an  arrangement. 


FIG.  23. — Arrangement  of  still  fitted  with  distillate  preheater. 

i  is  the  main  still ;  2,  the  main  vapour  pipe  ;  3,  the  distillate 
preheater  in  which  the  crude  is  heated  and  to  some  extent 
distilled  by  the  latent  heat  of  the  condensing  vapours ; 
4,  the  condenser  for  the  distillates  given  off  from  this  distillate 
preheater ;  5,  the  cooler  for  the  condensed  vapours  which 
issue  from  the  heating  coil  of  the  distillate  preheater ;  and 
6,  the  condenser  for  the  vapours  which  escape  condensation 
in  that  heating  coil. 

From  every  set  of  main  stills  and  distillate  preheaters, 
therefore,  three  distinct  distillates  may  be  obtained. 

The  following  table  will  give  some  idea  of  the  manner  in 
which  the  distillate  preheaters  function  : — 


168    PETROLEUM  AND  ALLIED  INDUSTRIES 


Per  cent,  distilling  in  Engler 

Sp.  gr. 

flask  up  to 

@i5°C. 

100°  C. 

i50°C. 

200°  C. 

250°  C. 

Portion  of  the  distillate  from  a  main 

still  condensing  the  distillate  pre- 

heater 

0-804 

— 

— 

57 

92 

Portion  of  same  distillate  escaping 

condensation  in  the  distillate  pre- 

heater,  but   condensed   in  water- 

cooled  condenser 

0783 

— 

51 

95 

all 

Vapour  distilled   off  from  the  dis- 

tillate preheater     .  . 

0-698 

76 

97 

all 

—  , 

In  a  complete  plant  arranged  on  this  system  (Fig.  24) 
the  crude  oil  enters  the  residue  heat  exchanger  D,  where 
it  is  heated  up  by  the  outgoing  residue  to  such  a  temperature 


FIG.  24. — Arrangement  of  continuous  bench  with  preheaters. 

that  it  may  even  begin  to  distil  the  vapours  condensing  in 
condenser  C  n.  The  temperature  to  which  the  crude  oil 
will  be  heated  depends  naturally  on  the  percentage  of 
residue  from  the  crude,  and  this  may  vary  between  very  wide 


DISTILLATION  OF  CRUDE  OIL  169 

limits  for  various  crudes.  The  crude  oil  then  passes  through 
the  distillate  preheaters  B  i ,  B  2  in  succession,  and  then  through 
the  main  stills,  A  i — 4,  finally  issuing  as  residue  from  the  last 
still.  The  preheaters  and  also  the  stills  are  arranged  in 
cascade  fashion,  the  former  naturally  at  a  higher  level  so 
as  to  allow  the  crude  oil  to  flow  by  gravity  through  the 
series. 

In  the  above  diagram, 

A 1—4  represent  the  main  stills. 

B  i — 2  two  double  distillate  preheaters,  each  containing 
two  separate  sets  of  coils. 

C  i,  C  4,  C  7,  C 10  coolers  for  the  portions  of  main  still 
vapours  condensed  in  the  preheaters. 

C  2,  03,  C8,  C  9  condensers  for  the  portions  of  main  still 
vapours  which  escape  condensation  in  the  preheaters. 

C  5,  C  6  condensers  for  the  vapours  from  the  preheaters. 

C  ii  condenser  for  vapour  from  residue  heat  exchanger. 

D  residue  crude  oil  heat  exchanger. 

With  such  an  arrangement  very  great  fuel  economy  is 
effected. 

As  a  general  rule  the  complete  distillation  of  a  crude 
oil  is  effected  in  two  stages.  In  the  first  stage  the  lighter 
fractions,  benzine  and  kerosene  distillates,  and  perhaps  a 
little  gas  oil  are  distilled  off.  In  certain  cases  no  further 
distillation  of  the  crude  is  necessary,  the  residue,  after  the 
removal  of  the  benzine  and  kerosene  being  marketed  as  a 
liquid  fuel. 

In  many  cases,  however,  it  is  desirable  to  work  up  this 
residue  further  as  (i)  it  may  be  too  asphaltic  and  thick  for 
use  as  fuel  oil  directly  as  is  the  case  with  many  Mexican 
and  Venezuelan  fuels ;  or,  (2)  it  may  contain  so  much 
paraffin  wax  as  to  make  the  extraction  of  this  worth  while, 
as  is  the  case  with  Pennsylvanian,  Mid-continent,  and 
Burmah  crudes,  for  example ;  or,  it  may  contain  valuable 
lubricating  oil  fractions,  which  can  be  removed,  e.g.  Russian 
crudes. 

As  much  higher  temperatures  are  required  for  completing 
this  distillation,  somewhat  different  arrangements  are 


170    PETROLEUM  AND  ALLIED  INDUSTRIES 

necessary,  consequently  the  second  stage  of  the  distillation 
is  usually  carried  out  in  a  separate  bench  of  stills. 

The  dephlegmators  for  lubricating  oil  stills  are  often 
replaced  by  a  series  of  horizontal  pipes  of  large  diameter, 
through  which  the  vapours  pass  on  their  way  to  the  main 
condenser.  From  each  of  these  large  pipes  a  condensate 
fraction  may  be  drawn  off.  These  condensates  will  usually 
be  dry,  as  the  steam  should  condense  only  in  the  condenser. 
During  distillation  for  lubricating  oil  fractions  and  for  paraffin 
wax  relatively  large  volumes  of  steam  are  blown  into  the  still 
to  avoid  cracking  of  the  oil  as  far  as  possible.  In  distilling 
off  the  higher  boiling-point  fractions,  the  amount  of  steam 
blown  into  the  still  may  exceed  the  amount  of  oil  distillate 
obtained. 

Certain  crude  oils,  e.g.  some  from  the  Pennsylvanian 
fields,  may  yield  a  cylinder  oil  residue  after  a  large  percentage 
of  the  crude  has  been  distilled  off.  Imbricating  oil  distillates 
also  are  often  concentrated  down  to  heavier  oils  or  cylinder 
oils.  In  this  case  care  has  to  be  taken  not  to  overheat  the 
oils,  copious  supplies  of  steam  being  used  for  this  purpose, 
and  the  fires  being  extinguished  some  time  before  the 
end  of  the  operation.  As  the  quality  of  the  distillates  is 
much  improved  by  distilling  under  high  vacuum,  this 
process  is  nowadays  often  applied. 

A  modern  successful  type  of  high  vacuum  plant  is  that 
designed  by  Steinschneider  (U.S.  Pat.  981953)  (Fig.  25). 

The  stills  used  (A)  are  of  the  usual  cylindrical  type  often 
fitted  with  an  internal  fire  tube.  They  are  strengthened 
internally  in  order  to  stand  the  external  pressure.  They 
are  arranged  in  a  bench  of  six  or  more  for  continuous 
working.  Each  still  is  fitted  with  one  or  more  domes 
connected  to  a  vapour  pipe  (B)  of  large  dimensions,  14 
inches  or  more,  in  order  to  allow  the  vapours  to  pass 
away  as  quickly  as  possible  so  as  to  maintain  a 
vacuum  in  the  still.  This  vapour  pipe  usually  bends 
back  on  itself  once  or  twice  forming  an  air-cooled  con- 
denser. Any  distillates  condensing  here  are  pumped  away 
through  a  cooler. 


DISTILLATION  OF  CRUDE  OIL 


171 


This  large  vapour  pipe  leads  into  an  air-cooled  dephlegm- 
ator  C,  in  which  a  further  fraction  condenses,  then  into 
a  further  water-cooled  dephlegmator  D,  in  which  the  bulk 
of  the  distillate  condenses.  The  vapours  then,  consisting 
mostly  of  steam,  pass  on  into  the  barometric  condenser  E, 
where  they  are  condensed  by  a  jet  of  water.  This  baro- 
metric condenser  is  placed  at  an  elevation  of  over  30  feet 
and  the  effluent  pipe  leads  downwards  to  a  water  seal  so 
that  the  condenser  forms  practically  a  water  barometer. 


FIG.  25. — Arrangement  for  distilling  under  high  vacuum. 

The  vent  of  this  condenser  is  connected  to  a  suitable  air 
pump. 

The  distillates  running  from  the  dephlegmators,  after 
passing  through  coolers  run  into  sealed  receiving  tanks  of 
small  capacity  (not  shown  in  the  diagram),  whence  they  are 
pumped  out  by  low-level  pumps  to  the  tail-house.  This 
arrangement  of  pumps  enables  the  distillation  plant  to  be 
constructed  without  the  necessity  of  making  each  distillate 
discharge  a  barometer  tube.  All  that  is  necessary  is  to 
make  the  height  of  the  discharge  pipes  equal  to  the  head 
which  the  pumps  can  easily  maintain  when  evacuating. 

Such  a  continuous  bench  of  high  vacuum  stills  can 


172    PETROLEUM  AND  ALLIED  INDUSTRIES 

easily  be  operated  at  a  pressure  of  only  10  or  15  centi- 
metres pressure  absolute,  and  under  these  conditions  the 
temperature  of  the  oil  in  the  still  need  not  exceed  300°  C., 
a  temperature  about  50°  lower  than  would  be  reached 
without  vacuum.  In  order  to  avoid  pumping  out  the  hot 
residue  from  the  last  still,  it  is  usual  to  operate  the  last  two 
stills  periodically  and  alternately,  so  that  the  one  when  its 
contents  are  distilled  as  far  down  as  desired,  may  be  cut 
out  from  the  vacuum  and  pumped  out  while  the  other  is 
being  rilled  and  functioning  as  last  still. 

Distillation  for  paraffin  wax  is  carried  out  in  similar 
continuous  plant,  usually  at  atmospheric  pressure.  The 
determination  of  the  setting  points  of  the  distillates  in  this 
case  indicates  how  the  distillation  is  proceeding. 

In  the  case  of  certain  crudes,  e.g.  some  of  the  Pennsyl- 
vanian,  practically  all  the  paraffin  wax  may  be  distilled  off, 
so  that  the  residue  in  the  still  may  be  used  as  a  so-called 
steam  refined  cylinder  oil.  In  the  case  of  other  crudes  it 
is  impossible  so  to  distil  off  the  bulk  of  the  wax ;  much 
remains  in  the  residue,  which  forms  a  very  thick  asphaltic 
substance,  too  thick  for  use  as  fuel.  Attempts  to  distil 
this  further  with  the  use  of  steam  would  result  in  the 
production  of  very  viscous  distillates,  containing  wax 
which  would  not  easily  crystallize.  Both  distillates  and 
residue  would  thus  be  very  difficult  substances  to  handle. 
This  thick  residue  is,  therefore,  usually  further  distilled 
in  so-called  "  tar  or  coking  "  stills.  These  are  special  stills  of 
strong  construction,  the  bottoms  of  which  are  usually  made 
in  one  piece.  They  are  usually  set  so  that  the  whole  of  the 
bottom  is  exposed  to  the  furnace  gases,  no  return  flues 
being  used.  They  are  often  fired  from  the  side  instead  of 
from  the  ends,  a  more  uniform  distribution  of  heat  being 
thus  obtained.  The  distillation  is  conducted  rapidly  with- 
out the  use  of  steam.  A  further  yield  of  paraffin  wax 
distillate  is  thus  obtained,  which  is  thin  and  easily  crystal- 
lizable  owing  to  the  presence  of  these  cracked  oils.  Towards 
the  end  of  the  distillation  the  stream  of  distillate  changes 
in  character  owing  to  the  presence  of  high  melting  point 


DISTILLATION  OF  CRUDE  OIL  173 

hydrocarbons  of  the  aromatic  type.  This  distillate  is  known 
as  "  wax  tailings."  When  the  bottom  of  the  still  shows  dull 
red,  the  fires  are  turned  out,  and  the  distillation  is  allowed 
to  complete  itself.  The  residue  is  then  a  petroleum  coke. 
After  cooling  somewhat  the  still  is  opened  and  the  coke  is 
dug  out.  The  life  of  a  still  subjected  to  such  strenuous  use 
is  naturally  short. 

In  the  case  of  crude  oils  rich  in  asphalt,  e.g.  the  heavy 
crudes  of  Mexico,  California,  and  Texas,  the  distillation 
may  be  conducted  so  as  to  produce  an  asphalt  to  definite 
specification.  Distillation  to  asphalt  is  usually  carried  out 
periodically  in  stills  of  large  capacity,  100  tons  or  more. 
The  distillation  may  also  be  conducted  in  continuous 
plants,  the  control  being  effected  by  examination  of  the 
outgoing  residue  rather  than  by  the  character  of  the 
distillates. 

In  order  to  obtain  asphalt  of  good  quality  it  is  necessary 
to  avoid  overheating,  particularly  as  the  periodic  distillation 
takes  a  considerable  time  (24  hours  or  more).  Copious 
supplies  of  steam  are  therefore  blown  into  the  still,  so  that 
towards  the  end  of  the  distillation,  three  or  four  times  as 
much  water  as  oil  is  condensed  in  the  condensers.  The 
distillates  produced  will  usually  be  gas  oils  or  perhaps  light 
lubricating  oil  distillate  according  to  the  grade  of  asphalt 
produced.  It  is  usual  not  to  allow  the  temperature  of  the 
oil  in  the  still  to  exceed  350°  C.  during  this  operation. 

During  the  last  few  years  stills  of  the  conventional  type 
have  been  to  some  extent  replaced  by  the  much  simpler 
tubular  stills.  The  development  of  this  type  of  plant 
arose  from  the  difficulty  of  handling  crude  oils  containing 
emulsified  water  in  ordinary  stills,  as  there  is  very  great 
danger  of  the  whole  contents  of  the  still  frothing  or  "  puking  " 
over  when  the  temperature  passes  100°  C.  The  distilling 
operation  must,  therefore,  be  carried  out  with  very  great 
caution.  The  idea  of  the  tubular  still  for  dehydrating  such 
crude  oils  was  developed  in  the  United  States  by  Bell,  Brown, 
Trumble,  and  others.  Its  use  was  then  extended  to  the 
distilling  off  of  light  fractions  from  heavy  crudes  in  order  to 


174    PETROLEUM   AND  ALLIED  INDUSTRIES 

raise  the  flash-point  to  liquid  fuel  standard.  From  this  the 
name  "  topping  plant  "  was  derived,  a  term  now  in  general 
use.  The  plant  has  now  been  considerabty  further  developed, 
so  that  its  use  extends  to  the  distillation  of  rich  crude  oils 
yielding  60  per  cent,  or  more  of  distillate,  and  to  the  distilla- 
tion of  heavy  crudes  down  to  asphalt.  The  principle  of 
such  plants  is  very  simple,  the  variations  in  construction 
found  are  very  numerous. 

In  general,  the  crude  oil  first  flows  through  a  series  of 
heat  exchangers  where  it  is  heated  by  the  condensing 
vapours  and  by  the  hot  residue.  It  then  flows  on  to  the 
tubular  retorts  which  consist  of  4-inch  tubes  set  in  a  furnace. 
In  passing  through  these  tubes  the  oil  is  partially  evaporated, 
and  any  water  it  may  contain  completely  so.  The  mixture 
of  oil  vapour  and  steam  then  passes  through  an  uptake  pipe 
to  some  form  of  separating  box  into  which  it  issues  as  a 
foam.  Separation  of  the  vapours  takes  place  here;  the 
vapours  pass  off  by  suitable  vapour  pipes  to  the  condensers, 
and  the  residue  passes  off  via  the  heat  exchangers  to  the 
residue  tanks. 

One  fundamental  difference  between  such  a  plant  and  a 
continuous  bench  of  stills  is  immediately  noticeable.  In 
the  case  of  the  continuous  bench  each  still  yields  a  certain 
fraction  ;  in  the  case  of  the  tubular  retorts  the  whole  of  the 
distillate  is  taken  off  at  once.  In  the  case  of  the  continuous 
bench  the  residue  in  the  last  still  is  in  equilibrium  with  the 
vapours  from  the  last  still  only,  whereas  in  the  separating 
box  of  the  topping  plant  the  residue  is  in  equilibrium  with 
the  whole  of  the  vapours.  For  any  given  percentage  of 
distillate,  therefore,  the  flash-point  of  the  residue  from  a 
topping  plant  will  be  somewhat  lower  than  that  from  a 
continuous  bench. 

The  taking  off  of  the  distillate  en  Hoc  necessarily  involves 
considerable  redistillation  in  order  to  effect  the  separation 
into  commercial  fractions.  This  can  be  and  usually  is, 
however,  effected  by  means  of  fractional  condensation  and 
partial  redistillation  by  means  of  the  heat  of  the  residue. 

A  description  of  a  modern  complete  plant  working  on 


DISTILLATION  OF  CRUDE  OIL  175 

this  system  will,  therefore,  be  given,  a  Trumble  plant  being 
selected  as  representative. 

The  heaters  or  retorts  are  made  up  of  4-inch  steel  pipes 
arranged  in  six  rows,  each  of  twelve  pipes,  placed  one  above 
the  other.  The  ends  of  these  pipes  are  connected  by  flanged 
return  bends,  which  may  be  removed  for  cleaning  purposes. 
These  bends  are  placed  outside  the  brickwork  setting  of  the 
retort,  and  may  be  insulated  either  individually  by  asbestos 
jackets,  or  by  being  enclosed  in  a  space  closed  by  folding 
doors.  The  whole  number  of  pipes  are  thus  connected  in 
series  as  a  single  tube.  Two  such  sections  are  set  side  by 
side  to  make  one  battery.  The  heating  is  effected  by  liquid 
fuel  firing,  the  arrangement  of  the  furnace  being  such  that 
direct  flames  do  not  play  on  the  tubes.  The  most  effective 
method  of  heating  is  naturally  the  counter  current  method, 
the  heated  flue  gases  descending  round  the  nest  of  tubes 
through  which  the  crude  oil  passes  upwards  (Fig.  26). 

The  internal  heating  surface  of  two  such  heaters  would 
be  2430  square  feet.  These  two  heaters  may  be  connected 
in  series  or  in  parallel  as  required.  Several  thermometers 
are  fitted,  so  that  the  temperature  of  the  crude  oil  as  it  flows 
through  the  system  may  be  accurately  controlled. 

Automatic  controlling  apparatus  may  now  be  obtained 
actuated  by  the  thermometer  placed  in  the  pipe  leading 
from  the  last  retort  to  the  vapour  separating  vessel.  In  this 
way  an  increase  of  temperature  can  be  made  to  bring  about 
an  acceleration  of  the  crude  oil-feed  pump  and  vice  versa,  so 
that  the  personal  element  can  be  eliminated  in  this  particular 
case. 

The  working  temperatures  will  naturally  depend  on  the 
nature  of  the  crude  oil  being  distilled  and  on  the  fractions 
to  be  distilled  off.  The  heated  crude  oil  leaves  the  heaters 
in  the  form  of  a  foamy  mixture  of  vapour  and  oil  and  passes 
by  an  uptake  pipe  which  discharges  into  the  top  of  the 
vapour  separating  vessel,  where  the  vapours  have  an 
opportunity  of  separating  themselves  from  the  residual  oil. 

In  the  case  of  the  Trumble  plant,  this  consists  of  a 
vertical  steel  cylinder,  6  feet  diameter  and  25  feet  high, 


176    PETROLEUM  AND  ALLIED  INDUSTRIES 


DISTILLATION  OF  CRUDE  OIL  177 

which  is  enclosed  in  a  brickwork  stack,  so  that  the  flue  gases 
from   the   heaters   can   pass   through   the    annular   space 


FIG.  27. — Trumble  evaporator  or  separating  vessel. 

separating   the   brickwork   from   the  steel   cylinder,    thus 

effecting  further  distillation.     Fitted  inside  this  vessel  is 

a  vertical  vapour  pipe  closed  at  the  top,  which  carries  a 
P.  12 


178    PETROLEUM  AND  ALLIED  INDUSTRIES 

number  of  umbrellas  the  outside  edges  of  which  extend 
almost  to  the  cylinder  walls.  The  object  of  this  arrangement 
is  to  ensure  the  liquid  flowing  down  the  sides  of  the  vessel. 
Directly  under  the  apex  of  each  umbrella  the  central  vapour 
pipe  is  perforated  so  that  the  vapours  may  enter.  One  or 
more  side  pipes  connected  to  this  central  vapour  pipe  allow  of 
the  vapours  being  led  off.  A  perforated  steam  coil  is  usually 
placed  at  the  bottom  of  this  "evaporator"  so  that  steam 
may  be  admitted  in  order  to  assist  in  the  distillation  (Fig.  27). 

An  oil  catcher,  consisting  of  a  small  vertical  cylinder 
2  feet  diameter  and  3  or  4  feet  high,  containing  a  number  of 
perforated  steel  baffle  plates,  is  placed  in  the  vapour  line,  to 
arrest  any  spray  of  heavy  oil  which  might  be  carried  over 
mechanically  with  the  vapours.  Such  an  arrangement  has 
already  been  mentioned  in  connection  with  an  ordinary 
distilling  plant  (p.  156). 

The  residue,  after  leaving  this  evaporator  or  separating 
vessel,  may  pass  off  through  crude  oil  heat  exchangers  or  may 
be  utilized  for  supplying  the  heat  necessary  for  redistilling 
some  of  the  fractions,  as  described  later.  The  residue-crude 
oil  heat  exchangers  are  usually  of  the  tubular  type.  The 
number  to  be  used  depends  on  the  nature  of  the  crude  and 
the  percentage  of  residue  obtained  from  the  plant. 

The  vapours,  after  leaving  the  separating  vessel,  pass 
on,  not  directly  to  the  main  condensers,  but  through  a 
series  of  "  dephlegmators  "  or  fractional  condensers.  These 
consist  of  vertical  steel  cylindrical  vessels  about  30  inches 
in  diameter  and  7  feet  high.  These  vessels  contain  a  number 
of  horizontal  saucer-shaped  baffle  plates.  Half  of  these  fit 
closely  to  the  walls  and  have  a  central  hole,  the  other  half 
placed  alternately  are  of  smaller  diameter  with  no  central 
hole.  The  vapours  thus  zigzag  through  the  annular  spaces 
and  central  holes.  The  heavier  fractions  condense  on  these 
plates  and  fall  back  to  the  bottom  of  the  dephlegmator, 
whence  they  are  led  off  by  a  special  pipe.  At  the  top  of  the 
dephlegmator  is  placed  a  water  coil,  by  means  of  which  a 
certain  amount  of  distillate  may  be  condensed  in  order  to 
furnish  a  quantity  to  flow  back  down  over  the  baffle  plates. 


DISTILLATION  OF  CRUDE  OIL 


179 


IT" 


In  this  way  the  dephlegmator  functions  to  some  extent  as  a 
fractionating  column  (vide  p.  190).  Further  below  the 
point  at  which  the  vapours  enter  the  dephlegmator  a  further 
number  of  baffle  plates  are  situated  and  means  is  provided 
for  blowing  in  steam  at  the  bottom,  so  that  the  down-flowing 
condensate  may  be  subjected  to  steam  distillation  (Fig.  28). 

The  main  vapours  pass 
through  several  (as  many 

as  eight  in  modern  plates)  1°  ?  °1  /  F°  °U-    I  OUTLET 

of  these  dephlegmators, 
being  thus  condensed  into 
as  many  condensates  which 
flow  from  the  bottom  of 
each  dephlegmator.  The 
vapours  from  the  last  de- 
phlegmator pass  on  into 
condensers  cooled  by  the 
entering  crude  and  finally 
into  water-cooled  coolers. 

These  various  distillates 
may  then  be  collected  sepa- 
rately in  the  tail-house,  or 
may  be  partly  redistilled 
in  the  ' '  separators . ' '  The 
separators,  several  of  which 
may  be  fitted,  consist  of 
rectangular  boxes  18  by  6 
feet  by  40  inches  high, 
along  the  bottoms  of  which 
run  several  3-inch  pipes 
connected  to  manifolds, 
through  which  hot  residue  can  be  run.  These  pipes 
are  supplemented  by  perforated  steam  pipes  through 
which  steam  can  be  blown.  To  the  top  of  these  boxes 
vapour  lines  are  attached.  These  separators  are  thus 
practically  stills.  The  condensates  from  the  dephlegmators 
which  require  further  distillation,  run  into  these  separator 
boxes  where  they  are  redistilled,  the  vapours  passing  through 


IML.ET 


d 

1°  °  °!    /£  ° 
poo    /  p-  o 

boo   ^jo  O( 

o 

0 

& 

X 

? 

^ 

^  e  J 

i 

r  • 

^~  . 

[ 

^-  • 

[ 

« 

6  . 

h 

/*-  * 

y 

< 

^  - 

) 

p-  - 

< 

) 

*  - 

•  —  » 

( 

•  '  •  " 

' 

« 

x^JQis>/ 

FIG.  28. — Dephlegmator. 


i8o    PETROLEUM  AND  ALLIED  .INDUSTRIES 

condensers  to  the  tail-house  and  the  residues  running  off 
through  coolers. 

The  accompanying  flow-sheet  diagrams,  Figs.  29  and  30, 


FIG.  29. — Course  of  crude  oil  and  residues  through  Trumble  plant. 

will  explain  the  several  courses  of  crude  oil,  residues  and 
vapours  through  the  plant.  These  diagrams  represent 
simple  cases  only,  and  must  not  be  taken  to  represent 


FIG.  30. — Course  of  vapours  through  Trumble  plant. 

actual  practice.  The  subject  of  topping  plants  or  tubular 
retort  distillation  plants  is  very  well  set  forth  in  Bulletin 
162,  Petroleum  Technology  45,  U.S.  Bureau  of  Mines,  by 


DISTILLATION  OF  CRUDE  OIL 


181 


J.  M.  Wadsworth,  where  very  full  details  as  to  plant  and 
operation  are  given. 

The  following  table,  giving  the  analyses  of  the  products 
obtained  from  the  dephlegmators  during  an-actual  run,  will 
illustrate  to  what  an  extent  the  total  distillates  taken  off 
en  bloc  may  be  separated  by  fractional  condensation  : — 


Sample  from 

Distillation  in  Engler  flask,  percentages 
boiling  over  up  to 

F.  b.  pt. 

Fl.-pt. 

100°  C. 

I50C. 

200°  C. 

250°  C. 

300°  C. 

Dephlegmator  i     .  . 

2      .  . 

3    •• 
4    •• 

6    '.'. 
Vapour  from   6    .  . 

7 

I 

87 

X3 
33 

70 

95 

5 
ii 

65 

90 

40 
78 

>350 
350 
299 
265 

235 
225 

175 

90°  C. 
75°  C. 
46°  C. 
33°  C, 
25°  C. 
i6°C. 

Of  the  above  products  Di  would  run  to  gas  oil,  D2  might 
be  worth  redistilling  to  extract  therefrom  some  kerosene, 
D3  and  D4  might  run  to  kerosene  distillate,  05  should  be 
redistilled  and  perhaps  D6.  The  vapour  from  6  would 
naturally  run  to  heavy  benzine.  The  work  of  the  separators 
is  exemplified  by  the  following  analyses  : — 


— 

100°. 

125°. 

150°. 

175°. 

200°. 

F.  b.  pt. 

Flash-point. 

Oil    running     to 

separator 

—  • 

— 

15 

53 

80 

235 

20°  C. 

Distillate       from 

separator 

—  . 

22 

7° 

93 

192 

—  . 

Residue          from 

separator 

— 



2 

38 

75 

245 

33°  C. 

It  will  be  seen,  therefore,  that  such  a  distillation  plant  is 
complete  in  itself,  as  it  yields  a  series  of  finished  products 
which  do  not  require  to  be  subjected  to  a  further  process  of 
redistillation.  Such  a  plant,  therefore,  presents  many  ad- 
vantages over  the  system  of  stills  and  redistillation  stills 
usually  employed.  It  is  more  compact,  much  less  steel 
is  required  in  its  construction,  the  need  for  tanks  for 


182     PETROLEUM  AND  ALLIED  INDUSTRIES 

intermediate  products  disappears,  there  is  minimum  loss  of 
heat  as  the  products  for  redistillation  are  not  cooled  before 
passing  into  the  separator,  i.e.  redistillation  stills.  The 
fuel  consumption  is  low  and  the  efficiency  relatively  high 
compared  to  those  of  an  ordinary  distilling  plant. 

Though  in  the  first  place  designed  for  dehydrating  or 


FIG.  31. — Details  of  header  for  tubular  still. 

topping  crude  oils,  the  system  has  been  extended  to  dealing 
with  crude  oils  yielding  as  much  as  60  per  cent,  of  distillates. 
In  such  cases,  however,  limitations  are  imposed  by  the  lack 
of  heat  necessary  for  redistillation,  owing  to  the  low  per- 
centage of  residue  available. 

Tubular  or  pipe  stills  are  now  coming  into  general  use 
for  various  purposes,  such  as  preheating  crude  oil  preparatory 


DISTILLATION  OF  CRUDE  OIL 


183 


to  pumping  it  through  long  pipe-lines,   and  for  cracking 
furnaces. 

It  is  obvious  that  the  circulation  of  the  oil  in  a  pipe  still 
must  be  much  better  than  can  be  possibly  attained  in  a 
cylindrical  still,  consequently  the  chances  of  overheating 
the  oil  are  much  less.  Even  if  coke  is  formed,  it  can  be 


FIG.  32. — Special  type  of  tubular  still  or  heater. 

easily  removed,  and  moreover,  if  coke  deposition  goes  so  far 
that  tubes  are  damaged,  then  these  can  be  quickly  and 
cheaply  replaced.  Patching  the  bottom  of  a  cylindrical  still 
is  a  difficult  and  expensive  job  and  unsatisfactory  when 
finished.  Much  better  heat  exchange  is  possible  as  oil  and 
furnace  gases  can  run  counter  current,  fuel  consumption 
being  thus  reduced.  Moreover,  the  still  can  be  designed  so 


184    PETROLEUM  AND  ALLIED  INDUSTRIES 

that  the  fuel  can  be  properly  burnt  in  a  suitably  designed 
furnace.  In  modern  types,  the  pipes  of  the  tubular  stills 
are  constructed  with  a  covering  of  cast-iron  corrugated 
sleeves,  similar  to  those  used  in  Foster  superheaters  (Fig.  31). 

One  of  the  difficulties  in  distilling  oils  at  high  tempera- 
tures, such  as  are  necessary  for  cracking,  whether  it  be  in 
cylindrical  or  tubular  stills,  is  the  deposition  of  coke  on  the 
still  walls.  Although  this  cannot  be  entirely  avoided  it  can 
be  minimized  in  the  case  of  tubular  stills  by  designing  the 
plant  so  that  the  tubes  are  not  exposed  to  direct  radiation. 
In  a  still  recently  designed  by  the  Power  Speciality  Company 
this  has  been  effected  in  an  ingenious  manner  (Fig.  32). 

In  the  roof  of  the  furnace  are  placed  a  series  of  tubes 
B,  through  which  the  crude  oil  to  be  distilled  is  first  circulated 
before  passing  to  the  main  heating  tubes  D.  The  portion 
of  the  roof  covering  the  combustion  chamber  is  lined  with  a 
covering  of  insulating  material,  so  that  the  pipes  in  this 
area  are  protected  from  direct  radiation.  The  pipes  in 
the  area  of  the  roof  directly  over  the  main  heating  tubes 
are  thus  not  exposed  to  any  extent  to  any  direct  radiation, 
and  their  presence  prevents  this  portion  of  the  roof  becoming 
red  hot.  Consequently,  the  main  heating  tubes  D  are 
protected  from  the  direct  radiation  which  they  would  receive 
from  the  roof  were  the  tubes  B  not  placed  there.  This 
arrangement  has  proved  very  efficient  in  practice  and  is 
undoubtedly  a  marked  advance  in  the  construction  of 
tubular  stills. 

The  efficiency  of  the  older  types  of  periodic  still,  with 
simple  furnace  settings  and  no  arrangement  of  heat 
exchangers,  must  have  been  low  indeed.  The  efficiency 
of  many,  if  not  most,  plants  operating  at  the  present 
day  leaves  much  to  be  desired.  A  simple  calculation, 
taking  the  specific  heat  of  oil  at  0*45  and  the  latent  heat 
at  70  calories,  would  show  that  a  fuel  consumption  of 
1*2  per  cent,  reckoned  on  the  crude  oil  treated  would  be 
theoretically  sufficient  to  distil  off  say  50  per  cent,  of  distil- 
lates, allowing  for  no  heat  exchange  arrangements  whatever. 

In  actual  practice,   with  no  heat  exchange,   distilling 


DISTILLATION  OF  CRUDE  OIL  185 

periodically  with  old-fashioned  plant,  a  fuel  consumption 
at  least  six  or  seven  times  as  high  would  be  required. 
Wadsworth  (U.S.  Bureau  of  Mines,  Bulletin  162)  cites  a 
case  where  the  overall  efficiency  of  a  battery  of  crude  oil 
stills  working  continuously,  fitted  with  residue-crude  oil 
heat  exchangers,  amounted  to  34*8  per  cent.  He  also  cites 
the  case  of  a  modern  Trumble  plant  adequately  supplied 
with  heat  exchangers  and  separators  as  57  per  cent.  Even 
such  a  figure  leaves  room  for  considerable  improvement 
when  it  is  considered  that  the  efficiency  of  modern  Spencer- 
Bonecourt  steam  boilers  is  actually  over  90  per  cent.  There 
is  no  reason,  however,  why  a  battery  of  continuous  crude 
oil  stills,  equipped  with  distillate  preheaters,  residue-crude 
oil  heat  exchangers,  and  heat  exchangers  placed  in  the  flues 
(after  the  fashion  of  a  Green's  economizer)  should  not  have 
an  efficiency  as  high  as  that  of  a  tubular  retort  distillation 
plant.  It  is  naturally,  however,  much  more  easy  to  ensure 
an  efficient  furnace  in  the  case  of  a  tubular  still.  With 
highly  efficient  continuous  batteries,  however,  the  fuel 
consumption,  when  distilling  an  oil  yielding  70  per  cent,  or 
so  of  distillate,  may  be  reduced  to  below  2  per  cent,  of  the 
crude  oil  distilled. 

The  methods  described  above  are  those  in  general  use 
in  the  petroleum  industry.  There  are  undoubtedly  still 
great  possibilities  in  the  direction  of  more  efficient  distilling 
plant.  One  of  the  great  objections  to  distilling  oil  at  high 
temperatures  in  any  usual  form  of  plant,  especially  in 
cracking  plants,  is  the  formation  of  coke  on  the  inside  of 
the  still  or  retorts.  Such  coke,  being  a  poor  conductor  of 
heat,  gives  rise  to  overheating  of  the  iron  plate  through  which 
the  heat  must  be  transmitted,  so  that  damage  soon  results. 
An  obvious  way  of  getting  over  the  difficulty  would  seem  to 
be  the  method  of  distillation  by  direct  contact  with  heated 
gases,  a  method  which  is  successfully  applied  to  the  concen- 
tration of  sulphuric  acid.  This  idea  is,  in  fact,  very  old. 
In  1860,  W.  Gossage  (Eng.  Pat.  1086)  patented  a  method  of 
distilling  bituminous  substances  by  injecting  highly  heated 
gases  obtained  by  the  combustion  of  suitable  fuel.  D alley 


186    PETROLEUM  AND  ALLIED  INDUSTRIES 


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DISTILLATION   OF  CRUDE  OIL  187 

(Eng.  Pat.  163347,  July  21,  1919)  proposes  to  inject  a 
spray  of  the  oil  to  be  distilled  on  to  the  surface  of  solid  fuel 
in  a  retort  or  producer,  air  for  combustion  being  blown  in 
at  the  bottom.  Knibbs  (Eng.  Pat.  165863  of  July  n,  1921) 
suggests  an  apparatus  based  on  the  same  principle. 

As  far  as  the  writer  is  aware,  this  method  of  distilling 
by  direct  contact  with  furnace  gases,  which  seems  to  present 
such  obvious  advantages,  has  not  as  yet  found  successful 
application. 

As  crude  oils  show  such  great  variation  in  character,  a 
definite  working  scheme  must  be  drawn  up  for  each  individual 
oil.  Two  diagrams  are  given  above  illustrating  typical 
methods  of  working  up  crude  oils. 

Fig.  33  illustrates  the  simple  case  of  working  up  a 
crude  oil  into  benzine  (motor  spirits),  kerosene,  gas  oil  and 
liquid  fuel  only,  the  fuel  residue  being  further,  perhaps, 
worked  up  into  lubricating  oils  and  asphalt. 

Fig.  34  represents  a  scheme  for  working  up  a  paraffin  wax 
base  crude  oil.  Reference  will  be  made  to  this  diagram  in 
further  sections  of  this  work. 


GENERAL   REFERENCES  TO   PART  VII.,   SECTION   A. 

Bacon   and   Hamor,   "  The   American   Petroleum   Industry, "   vol.  2 
McGraw  Hill. 

Campbell,  "  Petroleum  Refining."     Griffin  and  Co. 
Engler-Hofer,  "  Das  Erdol."  vol.  3.     Hirzel,  Leipzig. 
Wadsworth,  Bulletin  162,  U.S.  Bureau  of  Mines. 


SECTION  B.— REDISTILLATION  AND  FRAC- 
TIONATION   OF  LIGHT   OILS 

IT  has  been  pointed  out  that  in  the  ordinary  process  of 
distillation  of  crude  oil,  a  fraction  intermediate  between, 
or  rather  consisting  of,  benzine  and  kerosene  is  obtained. 
The  more  efficient  the  system  of  primary  distillation,  the 
smaller  this  fraction.  In  general,  however,  quantities  of 
such  distillate  must  be  redistilled  in  the  average  refinery. 
Moreover,  fractions  of  definite  boiling  ranges,  special  boiling- 
point  spirits,  white  spirits,  and  so  forth  are  often  required. 
For  the  manufacture  of  such  benzines  a  more  or  less  intensive 
fractionation  is  demanded. 

In  the  simplest  cases  a  separation  of  the  light  oils  into 
benzine  and  kerosene  only  is  required.  As  the  difference 
in  price  of  these  commodities  is  considerable  endeavours 
should  be  made  to  obtain  a  separation  as  sharply  as  possible. 
Generally,  however,  sufficient  attention  is  not  paid  to  this 
point  and  the  separation  is  by  no  means  well  effected.  The 
benzine  from  the  average  refinery  may  boil  up  to  200°  C., 
and  the  kerosene  may  have  as  much  as  30  per  cent,  boiling 
below  that  temperature. 

This  redistillation  is  usually  carried  out  in  so-called  steam 
stills,  which  may  be,  and  often  are,  operated  continuously. 
They  differ  little  from  ordinary  crude  oil  stills  chiefly  in  the 
mode  of  heating.  This  is  usually  effected,  as  the  name 
indicates,  by  means  of  steam.  Nests  of  high  pressure  steam 
coils  are  arranged  in  the  lower  part  of  the  still,  the  exits  being 
fitted  with  steam  traps.  Steam  at  pressures  up  to  160  Ibs. 
pressure  is  usually  employed.  This  enables  temperatures 
up  to  about  170°  C.  to  be  obtained  in  the  still.  As  in  the 

1 88 


REDISTILLATION  AND  FRACTION ATION    189 

case  of  crude  oil  distillation,  live  steam  is  also  blown  in  through 
perforated  pipes  lying  on  the  bottom  of  the  still  to  assist  the 
distillation. 

Direct  firing  may  also  be  employed,  but  in  some  cases 
this  tends  to  discolour  the  kerosene  residue  left  in  the  still, 
thus  rendering  necessary  a  more  intensive  treatment.  The 
control  by  means  of  steam  coils  is  easier,  but  the  fuel  con- 
sumption is  naturally  much  higher. 

The  steam  stills  are  usually  fitted  with  some  form  of 
simple  dephlegmator,  sometimes  water-cooled,  sometimes 
air-cooled.  In  many  cases,  however,  no  dephlegmator  is 
employed,  the  fractionation  being  so  much  the  less  efficient. 
In  cases  where  efficient  fractionation  is  required,  efficient 
columns  are  used. 

The  benzine-kerosene  distillate  is  distilled  in  such  stills 
until  the  residue  shows  the  requisite  flash-point,  care  being 
taken  that  the  final  boiling  point  of  the  distillate  does  not 
exceed  a  predetermined  value. 

The  following  table  shows  the  result  of  distilling  such  a 
benzine-kerosene  fraction  in  a  simple  steam  still  with  a 
simple  type  of  dephlegmator  : — 


Benzine-kerosene 

Engler  distillation.             distillation  before 
distillation. 

Benzine  distillate. 

Kerosene  residue. 

Up  to  125°  C. 

2  per  cent. 

. 

150°  C. 

4  per  cent. 

3i 

— 

175°  C. 

3i 

75 

— 

200°  C. 

65        „ 

98        ,, 

20  per  cent. 

225°  C. 

88 

all 

66 

250°  C. 

95 

— 

86 

27S°C. 

all 

— 

95 

Final  boiling  point 

265 

200 

285 

40  per  cent,  of  benzine  distillate  and  60  per  cent,  kerosene 
residue  being  obtained  in  this  case. 

The  benzine  distillate  would  be  mixed  with  the  straight- 
run  benzine  from  the  primary  distillation,  and  the  residue 
with  the  kerosene'  distillate.  The  percentage  of  benzine- 
kerosene  distillate  obtained  from  any  crude  oil  will  depend 


PETROLEUM  AND  ALLIED  INDUSTRIES 

on  (a)  the  nature  of  the  crude  oil,  (b)  the  efficiency  of  the 
primary  distillation.  In  practice,  for  example,  an  actual 
crude  oil  yielded  : — 

Straight-run  benzine  distillate  . .  11*3  per  cent. 

Benzine-kerosene  distillate        . .  15*7        ,, 

Direct  kerosene  distillate  . .  10*3        ,, 

Residue     . .          . .          . .          . .  61-5 

lyOSS       ....  .    .  .   .  .    .  I  '2 

The  straight-run  benzine  distillate  would  be  cut  so  as 
to  give  a  final  boiling  point  of  not  more  than  200°  C.  The 
direct  kerosene  distillate  would  be  cut  so  as  to  give  a  flash- 
point of  about  100°  F.  and  final  boiling  point  not  over 
say  280°  C.,  the  intermediate  fraction  being  redistilled  as 
described  above. 

In  many  refineries,  however,  quantities  of  benzines  of 
narrow  boiling  point  ranges  are  made.  Such  benzines,  for 
example,  are  "  lighting  spirits/'  used  for  producing  air  gas,  or 
"  petrol  gas,"  for  lighting  purposes.  Such  benzines  must  be 
very  volatile,  boiling  completely  below  100°  C.  For  dry- 
cleaning  purposes,  vegetable  seed  extraction,  and  so  forth, 
benzines  boiling  between  say  80°  C.  and  100°  C.,  or  100°  C. 
and  120°  C.  are  required ;  for  solvent  purposes  benzines 
boiling  between  100°  C.  and  150°  C.  may  be  demanded; 
and  for  "  white  spirits/'  or  "  mineral  turpentine/'  benzines 
boiling  between  140°  C.  and  200°  C.  may  be  required.  The 
manufacture  of  such  spirits  necessitates  the  use  of  efficient 
"fractionating  columns." 

The  equipment  necessary  for  such  distillation  consists 
of  a  still  of  the  usual  type,  a  fractionating  column  and  a 
dephlegmator  for  returning  a  supply  of  condensate  to  run 
back  through  the  column. 

Fractionating  columns  may  be  of  several  types,  e.g. 
simple  columns  fitted  with  baffle  plates,  bubbling  columns  of 
the  Heckman  type,  or  columns  of  the  absorption  type  filled 
with  rings  or  other  form  of  packing. 

Columns  fitted  with  perforated  plates  are  largely  used 


REDISTILLATION  -  AND   FRACTION ATION    191 

in  the  coal-tar  industry  for  the  extraction  of  toluene  and 
xylene  from  light  coal-tar  benzols.  The  vapours  pass 
upwards  through  the  perforated  plates,  being  subjected  to  a 
scrubbing  action  by  the  enforced  bubbling  through  the  layer 
of  liquid  on  the  plates.  Such  simple  columns  cannot, 
however,  be  well  controlled  as  the  plates  would  drain  dry 
when  running  slowly.  In  columns  of  the  Heckmann  type 
a  layer  of  liquid  is  maintained  on  the  plates,  the  up-going 
vapours  being  forced  to  take  one  path,  the  down-coming 
liquid  another.  The  action  of  such  a  column  is  best  explained 
by  reference  to  the  diagram  (Fig.  35) .  The  column,  which  may 
be  20  feet  high  and  5  feet  diameter, 
is  fitted  with  a  number  of  plates 
or  trays  9  inches  or  so  apart. 
Each  tray  is  fitted  with  one  or 
more  down-take  pipes,  the  top  of 
which  projects  a  short  distance 
above  the  tray,  and  the  bottom 
of  which  extends  almost  to  the 
underlying  tray,  projecting  below 
the  level  of  the  liquid  on  that 
tray,  so  that  the  lower  end  is 
sealed.  The  distance  to  which 
the  upper  end  of  the  liquid  down- 
take  pipes  A  project  above  the  FIG.  35. — Heckmann  column, 
tray  determines  the  depth  of 

liquid  which  remains  on  that  tray.  Bach  tray  is  fitted 
with  a  large  number  of  vapour  up-take  pipes,  the  upper 
ends  of  which  project  above  the  level  of  the  liquid  on 
the  tray.  These  up-take  pipes  are  covered  with  hoods, 
the  edges  of  which  are  usually  serrated  and  which  dip  into 
the  liquid  lying  on  the  tray.  The  vapours  are  thus  forced 
to  take  a  path,  bubbling  through  the  layers  of  liquid,  while 
the  returning  liquid  flows  back  down  the  column  by  the 
down-take  pipes. 

The  vapours  issuing  from  the  top  of  the  column  pass 
through  a  dephlegmator  on  their  way  to  the  condenser. 
In  this  dephlegmator  they  are  partially  condensed,  the 


ig2    PETROLEUM  AND  ALLIED  INDUSTRIES 

condensate  being  returned  by  a  sealed  pipe  to  the  column. 
The  amount  of  condensate  so  returned  to  the  column 
which  determines  the  efficiency  of  the  fractionation  may 
be  controlled  by  the  water  supply  admitted  to  the 
dephlegmator  (Fig.  36). 


FIG.  36. — Complete  fractionating  plant. 

By  means  of  such  a  column,  fractions  boiling  over  a 
range  of  only  a  few  degrees  C.  may  be  obtained. 

The  process  of  fractionation  as  it  goes  on  in  the  column 
is  well  exemplified  by  the  following  analyses  of  five  fractions 
taken  simultaneously  from  various  points  in  a  Heckmann 
column : — 


REDISTILLATION  AND   FRACTIONATION    193 


Samples  from 
column. 

Initial  boil- 
ing point. 

Distillation  in  Engler  flask.     Per  cent, 
boiling  up  to  temperatures  °C. 

Final  boil- 
ing ^int. 

105 

105/110 

110/115 

II5/I20 

120/125 

Top  I  .  . 

2  .  . 

3  -• 
4  .. 
Bottom  5 

98 

IOO 
101 
IO2 
103 

48 
37 
14 
4 

46 

54 
68 
66 
32 

8 
13 

21 

38 

4 
16 

4 

7 

112 
II4 
II7 
I24 
J34 

The  following  table  gives   analyses   of  samples  taken 
at  various  points  simultaneously  : — 


Sample.             ;  fP-  fj- 

Initial 
boiling 
point. 

Distillation  in  Engler  flask. 
Per  cent,  boiling  up  to  °C. 

Final 

boiling 
point. 

• 

°C. 

125° 

135°      150°      170° 

°C. 

! 

Liquid  in  still  .  .    !  0-766 

124 

22    '    68        91 

197 

Vapours  in  still      o'755 

no 

— 

— 

39 

—        94        all 

165 

Vapour  from  top 

of  column     .  .     0-739 

96 

49 

98 

— 

—        —        — 

no 

Liquid  returning 

from  dephleg- 

mator            .  .     0-743 

98 

16 

— 

— 

—    ,    —        — 

112 

Liquid  from  con- 

denser          .  .     0-734 

1 

94 

88 

— 

— 

—        —        —  , 

104 

Should  a  fraction  of  very  narrow  boiling  range  be  required 
redistillation  of  a  fraction  may  of  course  be  necessary. 

The  type  of  fractionating  column  filled  with  rings  or 
some  other  type  of  packing  is  as  yet  little  used  in  the 
petroleum  industry.  High  efficiency  is,  however,  claimed 
for  this  type  of  column.  It  presents  the  advantage  of  a 
very  great  wetted  surface  for  contact  between  vapour  and 
scrubbing  liquid. 

Raschig  (Bng.  Pat.  6288/14)  patented  simple  rings; 
modifications  of  such  rings  with  even  greater  surface  have 
been  patented  by  jessing,  Prym,  Goodwin,  and  others. 
These  rings  may  be  made  of  various  materials  and  dimensions. 
If  made  of  sheet  iron  25  mm.  high  and  25  mm.  diameter, 
55,000  may  be  packed  into  a  cubic  metre,  and  so  present 
a  total  surface  of  220  square  metres. 
P.  13 


194    PETROLEUM  AND  ALLIED  INDUSTRIES 

The  following  data  supplied  by  Dr.  I^essing  illustrate 
the  superiority  of  such  a  column  over  a  column  of  the  Coff  ey 
type  for  removing  benzol  from  a  solution  of  this  in  a  heavy 
green  oil.  In  this  particular  case  the  column  was  employed 
to  remove  the  benzol  from  the  scrubbing  liquid  used  for 
absorbing  the  benzol  from  coal  gas.  The  columns  compared 
were  of  the  same  height,  but  of  different  diameters,  that  of 
the  Coffey  column  being  2  feet,  that  of  the  ring  column 
1 8  inches.  The  volume  of  the  ring  column  was  therefore 
only  56  per  cent,  of  that  of  the  other. 


Coffey  column. 

Ring  column. 

Benzene  and  toluene  in  benzolized 

oil            

Benzene  and  toluene  in  debenzol- 

3-85  per  cent.  vol. 

3-8  per  cent. 

ized  oil    .  . 

I-35 

0-4 

Benzene    and    toluene    in    crude 

benzol  distilled  off 

73'5 

79'5 

Efficiency  of  recovery  of  benzene 

and  toluene 

66'i 

89-6 

Throughput  of  column  gallons  per 

day 

1065 

890 

These  figures  indicate  the  superiority  of  the  ring  column, 
especially  when  taking  into  consideration  its  much  smaller 
volume. 

The  objections  to  this  type  of  column  would  apparently 
be  the  difficulty  of  running  with  small  quantities  of  return 
liquid  and  the  possibility  of  channelling,  i.e.  of  the  vapours 
taking  the  path  of  least  resistance,  and  thus  diminishing 
largely  the  contact  area. 

Numerous  other  types  of  columns  have  been  patented. 
Those  designed  by  Kubierschky  (Chemical  Age,  June  21, 
1919,  p.  n)  are  designed  so  that  the  hot  vapours  enter  at 
the  top  of  each  compartment  of  the  column  and  leave  at  the 
lowest  point,  passing  from  one  compartment  to  another  by 
vapour  up-take  pipes  leading  from  the  bottom  of  any  one 
compartment  to  the  top  of  that  immediately  above  it,  while 
the  liquid  flows  back  through  the  finely  perforated  plates 
which  form  the  bottoms  of  the  compartments. 


REDISTILLATION   AND  FRACTION ATION    195 

The  fuel  consumption  for  carrying  out  such  distillation 
is  necessarily  high  owing  to  the  large  quantity  of  distillate 
which  is  condensed  and  returned  to  the  still  to  be  again 
distilled.  The  amount  of  distillate  obtained  per  ton  of 
steam  used  in  a  simple  distillation  without  fractionation 
may  amount  to  10/12  times  the  amount  obtained  when 
distilling  to  obtain  a  fraction  of  20°  range  of  boiling  point. 

Several  such  stills  with  columns  may  be  arranged  to 
work  in  series  continuously.  Such  plants  do  operate  and 
successfully  separate  benzene,  toluene,  and  xylene  contin- 
uously from  crude  coal-tar  naphtha. 

Really  intensive  fractional  distillation,  however,  is  not 
adopted  in  the  petroleum  industry.  The  isolation  of  pure 
products  from  petroleum  by  distillation  on  the  large  scale 
would  be  very  difficult  if  not  impossible,  and  would  be  so 
costly  as  to  be  quite  out  of  court  as  a  commercial  process. 
The  subject  of  commercial  fractional  distillation  can  be 
much  better  studied  in  connection  with  the  coal  tar,  alcohol, 
and  other  industries. 


GENERAL  REFERENCES   TO   PART  VII.,   SECTION  B. 

Gay,  "  Distillation  et  Rectification,"  Chemie  et  Industrie,  vol.  3,  p.  491. 
Hausbrand, "  Die  Wirkungsweise  der  Rektificir-  und  Destillir-Apparate." 
Mariller,  "  La  Distillation  Fractionee."     Dunod  et  Pinat. 
Thorpe,  "  Dictionary  of  Applied  Chemistry,"  p.  263.     Longmans. 
Ullmann,  "  Enzyklopadie  der  Technische  Chemie,"  Part  III.  p.  719. 
Urban  and  Schwarzenberg,  Berlin. 

Warnes,  "  Coal  Tar  Distillation."     J.  Allen  and  Co. 


SECTION  C.— THE   CHEMICAL   TREATMENT 
OF  PETROLEUM  AND  SHALE   OILS 

THE  products  obtained  by  distillation  are  comparatively 
seldom  marketable  without  chemical  treatment.  Benzines 
from  certain  crudes,  e.g.  those  of  Sumatra,  are,  however,  so 
free  from  bad  smelling  and  objectionable  constituents  as  to 
be  directly  marketable,  but  kerosenes  and  lubricating  oil 
distillates  practically  always  need  refining. 

The  particular  method  of  treatment  employed  depends 
largely  on  the  nature  of  the  product  to  be  treated,  and  on 
the  extent  to  which  it  is  desired  to  improve  the  quality. 
In  the  case  of  benzines  which  are  to  be  used  for  such  purposes 
as  the  extraction  of  edible  oils  from  seeds,  the  removal  of 
all  objectionable  constituents  is  of  prime  importance.  The 
impurities  usually  present  are  sulphuretted  hydrogen  and 
organic  sulphur  compounds  of  the  mercaptan,  thioether,  or 
thiophene  type.  In  some  cases,  particularly  when  ' '  cracked  ' ' 
products  are  present,  reactive  unsaturated  hydrocarbons 
must  be  removed.  In  rare  cases  pyridins  may  be  found  as 
impurities,  and  in  benzines  derived  from  the  distillation  of 
shale  oils  or  coal  tars  phenols  may  also  be  present.  The 
removal  of  phenols  and  pyridins  presents  no  difficulties,  the 
usual  methods  of  washing  with  dilute  alkali  and  dilute  acid 
being  adopted  as  in  the  coal-tar  industry. 

The  removal  of  certain  sulphur  compounds  or  the 
desulphurizing  of  oils  is  a  problem  which  has  excited  the 
interest  of  many  chemists,  but  has  not  so  far  met  with  any 
solution  of  general  application.  Sulphuretted  hydrogen 
may  easily  be  removed  by  means  of  strong  caustic  soda 
alone.  The  other  sulphur  compounds  present  difficulties. 

196 


TREATMENT  VF  PETROLEUM  OILS        197 

This  problem  is  of  particular  importance  in  the  case  of 
shale  oils.  Such  oils  usually  contain  sulphur  compounds, 
sometimes  to  a  considerable  extent,  so  that  the  actual 
sulphur  content  may  sometimes  be  as  high  as  7  or  8  per  cent. 
Any  method  devised  for  the  desulphurizing  of  oils  must, 
of  course,  not  only  be  a  technical  but  a  commercial  success. 
The  cost  of  the  refining  process  must  be  reasonable. 

Strange  to  say,  the  method  of  refining  first  introduced 
is  still  that  in  most  general  use  to-day.  Sulphuric  acid 
is  the  agent  mostly  used.  This  method  of  treatment  is 
in  general  use  for  benzine,  kerosene,  and  lubricating  oil 
distillates.  In  general  principle  the  method  adopted  for 
these  three  distillates  is  the  same.  The  benzine  is  violently 
agitated  in  a  suitable  vessel  with  the  necessary  percentage 
of  concentrated  sulphuric  acid,  the  tarry  residue  separates 
out  and  is  drawn  off,  the  benzine  is  washed  with  water, 
treated  with  caustic  alkali,  and  again  washed.  The  acid 
treatment  is  usually  given  in  two  or  three  portions,  the  sludge 
being  drawn  off  before  the  addition  of  the  next  charge. 
Generally,  amounts  of  acid  up  to  2  per  cent,  or  even  more 
may  be  used  in  the  case  of  benzines ;  in  the  case  of  certain 
lubricating  oil  distillates  as  much  as  25  per  cent,  of  acid 
may  even  be  necessary.  Economy  may  often  be  effected 
by  using  the  sludge  from  the  second  or  third  treatment,  as 
acid  for  the  first. 

The  function  of  the  sulphuric  acid  is  not  fully  under- 
stood. It  appears  to  act,  certainly  in  the  first  application, 
as  a  drying  agent ;  it  undoubtedly  absorbs  unsaturated 
hydrocarbons  and  even  aromatics,  and  it  removes  also 
oxygenated  bodies.  It  undoubtedly  also  acts  to  some 
extent  as  an  oxidizing  agent,  as  sulphur  dioxide  is  usually 
evolved  during  the  refining  process.  The  strength  of  the 
acid  is  an  important  factor.  If  this  falls  below  97  per  cent, 
the  efficiency  rapidly  diminishes. 

Oleum  of  various  strengths  may  be  used,  but  it  must 
be  remembered  that  the  stronger  the  acid,  the  more 
readily  aromatic  hydrocarbons  are  sulphonated.  As  these 
hydrocarbons  are  the  most  valuable  from  a  motor  fuel  point 


198    PETROLEUM  AND  ALLIED  INDUSTRIES 

of  view  (vide  Ft.  VIII.,  Sect.  A),  it  is  advisable  to  avoid 
their  removal  during  the  treating  process  as  far  as  possible. 
The  presence  of  nitric  acid  in  the  sulphuric  acid  is  un- 
desirable, as  this  will  form  nitro-compounds  with  aromatic 
hydrocarbons  which  will  give  a  yellow  tinge  to  the  finished 
products.  The  presence  of  selenium  dioxide  is  stated  to 
have  the  same  effect.  It  is  commonly  observed  that 
distillates  which  have  been  standing  for  a  long  time  are 
more  difficult  to  refine. 

After  the  successive  acid  treatments  the  benzine  is 
allowed  to  stand  until  all  the  acid  sludge  has  settled  down. 
This  is  then  drawn  off,  the  benzine  is  washed  with  water 
and  then  neutralized  with  caustic  soda.  Of  this,  usually 
only  a  very  small  percentage  is  required.  A  further  wash 
with  water  after  draining  off  the  soda  sludge,  usually  com- 
pletes the  process. 

Mixing  is  effected  by  either  mechanical  means  or  by 
blowing  in  of  air.  In  either  case  the  operation  is  usually 
conducted  in  an  "  agitator."  This  consists  of  a  steel  cylin- 
drical vessel  fitted  with  a  conical  bottom.  The  capacity 
is  usually  not  over  20  tons  for  mechanically  operated 
plant,  but  when  air-mixing  is  used,  vessels  of  200  tons 
or  more  capacity  may  be  employed  (Fig.  37).  In  either 
case  the  agitator  is  fitted  with  an  inlet  pipe  for  the  benzine, 
and  inlet  pipes  for  acid  and  soda.  The  chemicals  may  be 
blown  up  into  the  agitators  by  means  of  montejus,  or  may 
be  run  in  from  measuring  tanks  placed  above.  The  latter 
is  the  preferable  method. 

Mechanical  agitators  are  fitted  with  a  central  shaft 
carding  some  sort  of  propeller.  The  whirling  round  of  the 
contents  of  the  agitator  as  a  whole  is  avoided  by  baffle 
plates  dipping  just  below  the  surface  of  the  liquid.  Such  an 
arrangement  produces  a  very  lively  agitation  and  thorough 
mixing  of  the  liquids.  In  the  case  of  air-operated  agitators, 
the  air  is  led  down  into  the  tip  of  the  cone  by  means  of  a 
4-inch  pipe.  The  agitator  (or  at  any  rate  the  conical 
portion)  is  often  lined  with  lead. 

The  top  of  the  agitator  is  completely  closed  in,   and 


TREATMENT  OF  PETROLEUM  OILS        199 

usually  fitted  with  a  number  of  explosion  doors.  These 
are  arranged  so  as  to  open  outwards,  and  automatically 
fall  back  into  position.  Steam  pipes  are  also  usually  led 
into  the  top  of  the  agitator.  This  is  advisable,  as  the 
vapours  above  the  liquid  have  often  been  known  to  flash. 
Should  this  occur  the  explosion  doors  fly  open  and  relieve 
the  pressure,  thus  preventing  the  roof  of  the  agitator  from 
being  blown  off.  It  is  in  some  refineries  common  practice 
to  blow  steam  into  the  top  of  the  agitator  during  the  period 


MI*   tHt.fr    -*•  : 


i 


FIG.  37. — Agitators. 

of  introduction  and  mixing  with  soda,  as  this,  strangely 
appears  to  be  the  danger  point. 

At  the  bottom  of  the  cone  is  placed  a  main  valve  con- 
nected to  a  cross  piece,  by  means  of  which  the  acid  sludge, 
waste  soda,  washings,  and  the  finished  product  may  be  drawn 
off  to  their  various  receptacles  (Fig.  37). 

In  the  case  of  benzines,  agitation  by  means  of  air  is 
inadvisable  owing  to  the  large  evaporation  losses  caused. 
Where  the  refining  loss  may  be  less  than  i  per  cent,  when 
mechanical  agitation  is  used,  it  may  be  more  than  double 


200    PETROLEUM  AND  ALLIED  INDUSTRIES 

that  amount  when  air  agitation  is  used,  particularly,   of 
course,  in  a  warm  climate. 

The  method  of  treatment  as  outlined  above  is  that  in 
most  general  use  for  benzines  and  kerosenes.  For  lubricating 
oil  the  techniqiie  of  the  method  is  somewhat  different  (vide 
p.  203) .  The  same  method  is  sometimes  applied  to  the  treat- 
ment of  paraffin  wax,  and  it  will  be  remembered  that  sulphuric 
acid  is  also  used  for  the  refining  of  ozokerite  or  natural  wax. 

Many  sulphur-containing  oils,  however,  do  not  readily 
yield  sweet-smelling,  marketable  products  by  such  a  com- 
paratively simple  treatment.  Numerous  methods  for  treat- 
ment of  such  oils  have  been  described,  but  comparatively 
few  are  in  successful  operation.  Certain  of  these  methods 
are  directed  to  remove  the  sulphur  from  the  crude  oil.  In 
many  cases,  such  as,  for  example,  the  crudes  of  Mexico, 
rich  in  asphalt,  of  which  sulphur  is  an  essential  or  consti- 
tutional component,  such  a  method  would  be  inapplicable. 
The  problem  of  desulphurizing  the  crude  is,  however,  of 
relatively  minor  importance  as  there  is  no  objection  to  the 
presence  of  sulphur  compounds  in  a  fuel  oil  or  asphalt.  A 
method  applied  to  the  crude  oil  is  that  designed  by  Frasch 
(/.  Ind.  and  Eng.  Chem.,  vol.  4,  p.  134).  The  sulphur 
rich  crude  oils  of  Canada  and  Ohio  are  distilled  in  a  flat- 
bottomed  cylindrical  still  in  presence  of  copper  oxide.  The 
still  is  fitted  with  a  vertical  shaft  carrying  horizontal  arms, 
to  which  hanging  chains  are  attached.  By  this  means  the 
copper  oxide  is  kept  in  suspension  in  the  oil.  After  the 
bulk  of  the  oil  has  distilled  off,  a  further  charge  is  added 
and  the  process  repeated,  and  this  may  be  carried  out  four 
or  five  times.  The  residue  and  the  copper  oxide  are  then 
pumped  out  through  a  filterpress,  the  copper  oxide  being 
thus  separated  off  and  regenerated  by  roasting.  The  same 
process  is  sometimes  carried  out  in  another  way,  the  vapours 
of  the  distillate  being  made  to  traverse  a  cylindrical  vessel 
in  which  revolves  a  steel  brush,  dipping  into  a  mixture  of 
heavy  oil  and  copper  oxide  in  the  lower  part  of  the  vessel. 
The  vapours  passing  through  the  teeth  of  the  revolving 
brush  are  thus  subjected  to  the  copper  oxide  and  so  refined. 


TREATMENT  OF  PETROLEUM  OILS        201 

Another  method  in  common  use  is  that  in  which  sodium 
plumbite  is  used.  The  benzine  (or  kerosene)  is  treated 
with  a  saturated  solution  of  litharge  (PbO)  in  strong  caustic 
soda.  A  heavy  black  sludge  is  formed  and  the  benzine 
remains  black  owing  to  the  presence  of  suspended  lead 
sulphide.  A  trace  of  flowers  of  sulphur  is  usually  added, 
which  completes  the  precipitation  of  the  lead  sulphide. 
After  drawing  off  the  sludge,  the  benzine  or  kerosene  is 
washed  with  water.  This  process  may  be  used  in  connection 
with  the  ordinary  acid  treatment. 

Innumerable  other  methods  of  treatment  have  been 
devised.  Colin  and  Amend  (U.S.  Pat.  723368  of  March  24, 
1903)  recommend  the  use  of  an  alkaline  hypochlorite  in 
presence  of  a  catalytic  agent,  such  as  manganese  dioxide. 
Dunstan  (Eng.  Pat.  139233)  uses  an  alkaline  hypochlorite 
and  regenerates  this  elect rolytically  after  use.  H.  A.  Frasch 
(U.S.  Pat.  525811  of  1894)  also  advises  the  use  of  a  hypo- 
chlorite. Hall  (Eng.  Pat.  26756  of  1913)  recommends  the 
use  of  sulphur  dioxide,  followed  by  a  distillation,  claiming 
that  a  large  amount  of  the  sulphur  is  thereby  converted 
into  a  form  which  may  be  easily  removed  by  the  ordinary 
methods. 

The  refining  of  shale  oil  benzines  and  cracked  benzines 
presents  difficulties  owing  to  the  presence  of  unsaturated 
hydrocarbons.  Treatment  with  a  dilute  sulphuric  acid 
(80  to  90  per  cent.)  often  suffices  to  remove  the  more 
objectionable  of  these,  particularly  the  diolefines  wrhich 
readily  condense  up  to  form  resinous  bodies.  Brooks  and 
Humphrey  (/.S.C.7.,  1918,  3i6A)  have  investigated  this 
question  and  have  concluded  that  during  the  refining  by 
sulphuric  acid  two  actions  take  place  simultaneously,  viz. 
the  olefines  are  partly  removed  and  partly  polymerized, 
neutral  alkyl  esters  being  formed  at  the  same  time.  These 
latter  and  the  polymerized  products  may  remain  in  the 
oil,  and  account  for  the  increase  of  specific  gravity  some- 
times noticed  in  refining  such  benzines. 

Methods  of  refining  cracked  benzines,  dependent  on  the 
use  of  colloidal  or  absorbent  substances  have  been  proposed. 


202    PETROLEUM  AND  ALLIED  INDUSTRIES 

Hall  (Kng.  Pat.  12100  of  1917)  proposes  passing  benzine 
vapours  through  fuller's-earth,  kept  at  a  temperature  above 
the  final  boiling  point  of  the  benzine.  The  columns  of 
fuller's-earth  are  kept  at  constant  temperatures  by  means  of 
oil  baths,  and  the  benzine  vapours  are  passed  through  the 
columns  in  series.  It  is  claimed  that  the  issuing  vapours 
when  condensed  have  completely  lost  the  odour  characteristic 
of  cracked  spirit.  The  fuller's-earth  appears  to  have  the 
power  of  causing  polymerization  of  the  unsaturated  hydro- 
carbons to  take  place,  so  that  high  boiling  condensation 
products  are  formed  which  may  be  drawn  off  from  the 
columns.  The  fuller's-earth  in  course  of  time  loses  its 
efficacy  and  needs  regeneration,  after  which  it  can  be 
reused. 

The  methods  of  refining  above  described  are  in  the  main 
applicable  to  kerosene  also.  The  application  of  these 
methods,  while  producing  a  kerosene  which  is  perfectly 
"  sweet,"  may  still  yield  a  product  of  which  the  colour  is 
not  up  to  the  required  standard.  The  colour  may  readily 
be  improved  by  mixing  the  kerosene  with  a  small  percentage 
of  some  decolorizing  powder,  and  allowing  the  powder  to 
settle  out  or  filtering  it  off.  Various  decolorizing  powders 
may  be  used  for  this  purpose,  e.g.  animal  charcoal,  a 
bone  black,  the  many  varieties  of  fuller's-earth,  e.g.  the 
American  floridin,  the  German  frankonit  and  so  forth. 
Certain  types  of  bauxite  also  function  well. 

The  action  of  these  decolorizing  powders  is  so  erratic 
that  general  working  rules  cannot  be  laid  down.  Some 
powders  in  the  case  of  certain  kerosenes  may  act  best  in  their 
ordinary  air-dried  state,  some  may  work  better  if  dried  at 
105°  C.,  and  others  only  if  previously  ignited.  For  any 
particular  kerosene,  powder  A  may  be  found  better  than 
B,  yet  for  another  type  of  kerosene,  powder  B  may  be 
found  better  than  A.  It  is  of  the  utmost  importance, 
therefore,  to  examine  thoroughly  the  effect  of  the  possible 
powders  on  the  kerosene  in  question  before  beginning 
operations. 

It  will  generally  be  found  that  the  animal  charcoals  are 


TREATMENT  OF  PETROLEUM  OILS        203 

much  more  efficient  (per  percentage  used)  than  are  the 
fuller's-earths,  but  they  are  usually  much  too  expensive. 
As  a  general  rule,  also,  f tiller 's-earth  works  better  if  pre- 
viously ignited  or  at  least  if  previously  dried  at  105°  C. 
Many  of  these  fuller's-earths  may  be  regenerated  and  reused, 
as  is  also  the  case  with  bauxite. 

In  the  case  of  kerosene,  the  decolorizing  powder  may  be 
introduced  into  the  ordinary  agitator,  and  the  mixture  run 
off  into  a  settling  tank.  In  order  that  the  last  traces  of  the 
powder  may  be  removed,  the  kerosene  should  be  filtered 
through  paper  in  filter  presses,  or  may  be  centrifuged  by 
means  of  a  Gee  centrifuge. 

The  chemical  treatment  of  lubricating  oils  and  waxes 
are  carried  out  on  similar  lines,  certain  necessary  modifica- 
tions being  introduced. 

The  treatment  of  lubricating-oil  distillates  with  sulphuric 
acid  is  usually  carried  out  in  an  agitator  constructed  some- 
what similarly  to  that  used  for  kerosene.  The  agitators 
are  usually  of  somewhat  smaller  capacity,  of  greater 
diameters,  and  less  depth.  They  may  be  provided  with 
steam  coils  for  heating  purposes.  The  agitation  is  invariably 
effected  by  means  of  air.  I^arge  percentages  of  acid  up  to 
20  per  cent,  or  more  may  be  used,  especially  for  the  heavier 
oils.  After  agitation  the  mixture  is  usually  run  out  into  a 
settling  tank  of  large  diameter,  in  which  the  acid  sludge 
may  more  easily  separate  out.  This  acid  sludge,  in  the 
case  of  heavier  oils,  may  be  practically  solid  and  may 
require  digging  out.  The  supernatant  oil,  after  thorough 
settling,  is  drawn  off  and  transferred  to  the  soda  agitator, 
where  it  is  neutralized  with  white  dilute  caustic  soda  with 
gentle  agitation  and  then  washed.  Great  care  must  be 
taken  with  the  neutralizing  and  washing  as  emulsions  may 
form,  the  subsequent  splitting  up  of  which  may  give  great 
trouble. 

The  colour  and  appearance  of  the  finished  oil  will  depend 
to  a  great  extent  on  the  thoroughness  of  the  separation 
from  the  acid  sludge.  Inefficient  washing  of  the  soda 
treated  oil  will  result  in  the  presence  of  soaps  in  the  finished 


204    PETROLEUM  AND  ALLIED  INDUSTRIES 

oil.  After  thorough  washing  the  oil  is  usually  warmed  and 
blown  dry  by  passing  air  through  it.  This  must  be  done  at 
a  temperature  not  too  high,  not  exceeding  50°  C.,  otherwise 
the  oil  may  go  off  colour  somewhat.  Various  modifications 
of  this  method  have  been  suggested  and  are  in  operation, 
e.g.  the  use  of  sodium  silicate  in  place  of  caustic  soda,  the 
use  of  lime  or  soda  lime  for  neutralization  in  place  of  soda. 

A  great  number  of  lubricating  oils  are,  however,  made 
without  any  acid  and  soda  treatment  at  all.  Such  are  the 
filtered  cylinder  oils,  filtered  neutral  oils,  and  many  others. 

The  filtration  is  effected  through  one  of  the  decolorizing 
powders  above  mentioned.  The  operation  is  simple.  The 
filtering  powder,  usually  granulated  and  free  from  fine 
dust,  is  filled  into  a  vertical  cylindrical  vessel,  resting  on 
filter  cloth  supported  on  horizontal  grids.  The  filtering 
vessel  is  steam  jacketed,  and  fitted  with  manholes  or  a 
removable  bottom  for  extracting  the  powder  after  use. 
The  heated  lubricating  oil  distillate  is  allowed  to  per- 
colate upwards  through  the  filtering  medium.  The  first 
fractions  which  pass  through  may  be  only  slightly  coloured, 
but  the  colour  grows  in  depth  as  filtration  proceeds.  By 
collecting  the  filtered  oil  in  separate  vessels  several  grades 
may  be  produced.  After  the  filtering  has  proceeded  as  far  as 
is  deemed  advisable,  the  vessel  is  disconnected  and  allowed 
to  drain.  Benzine  is  then  passed  through  the  vessel  in 
order  to  dissolve  out  the  oil  adhering  to  the  fuller's-earth, 
this  benzine  being  subsequently  recovered  by  distillation, 
After  thus  washing  the  fuller's-earth,  steam  is  passed  through 
to  remove  the  last  traces  of  benzine.  The  vessel  is  then 
opened  and  the  fuller's-earth  removed  for  regeneration. 
The  behaviour  of  the  fuller's-earth  should  be  investigated 
before  use  in  order  to  find  out  the  best  conditions  for 
use.  The  decolorizing  action  of  fuller's-earth  is  doubt- 
less a  physical  one,  the  asphaltic  bodies  being  absorbed. 
Gurwitsch  maintains  that  the  fuller's-earth  exerts  a  poly- 
merizing action  on  the  unsaturated  compounds,  an  opinion 
shared  by  Hall  (vide  p.  202). 

The   method   of   refining   by   mixing   with   decolorizing 


TREATMENT  OF   PETROLEUM  OILS        205 

powder  is  also  applied  to  the  manufacture  of  paraffin  wax. 
This  is  described  in  Section  D,  dealing  with  that  product. 

The  Edeleanu  Process. — The  above-mentioned  pro- 
cesses for  the  refining  of  oils  apply  generally  to  the  removal  of 
small  percentages  of  constituents  (so-called  impurities),  the 
presence  of  which  is  considered  objectionable.  The  kerosene 
fractions  of  certain  crude  oils,  notably  those  of  Borneo,  and 
to  a  less  extent  those  of  Rumania,  contain  appreciable 
quantities  of  aromatic  hydrocarbons,  the  presence  of  which 
renders  the  oil  of  relatively  poor  burning  quality  when  used 
in  ordinary  lamps.  (When,  however,  burned  in  lamps  of 
suitable  design  such  aromatic  kerosenes  can  give  excellent 
results.) 

The  problem  in  refining  such  oils  is,  therefore,  that  of 
removing  a  relatively  large  percentage  of  aromatic  hydro- 
carbons. This  could,  of  course,  be  done  by  sulphonation, 
but  in  this  case  the  splitting  up  of  the  sulphonic  acids  formed 
and  the  regeneration  of  the  sulphuric  acid,  are  problems  of 
great  technical  difficulty.  The  process  designed  by  Edeleanu 
(U.S.  Pat.  911553,  Eng.  Pat.  11140  of  1908)  is  a  physical 
process  in  which  the  above-mentioned  difficulties  do  not 
appear.  This  process  depends  on  the  use  of  liquid  sulphur 
dioxide  as  a  solvent  for  unsaturated  and  aromatic  hydro- 
carbons. Naphthenes  and  paraffins  are  relatively  insoluble 
in  this  reagent. 

The  principle  of  the  process  is  simple.  The  kerosene 
to  be  treated  is  agitated  with  a  large  volume  of  liquid 
sulphur  dioxide  at  a  low  temperature,  say  — 10°  C. 
Separation  into  two  layers  takes  place,  the  lower  being 
a  solution  of  the  aromatic  hydrocarbons  in  liquid  sulphur 
dioxide,  the  upper  the  naphthenes  and  paraffins,  con- 
taining some  sulphur  dioxide  in  solution.  These  layers 
are  separated  and  the  sulphur  dioxide  is  separated  off  by 
distillation,  recondensed,  and  used  over  again.  The  sulphur 
dioxide  works  thus  in  a  cycle,  so  that  only  working  losses 
need  be  made  up. 

By  the  Edeleanu  process  also  the  sulphur-containing 
bodies  occurring  as  impurities  may  also  be  removed. 


206    PETROLEUM  AND  ALLIED  INDUSTRIES 

Several  large-scale  plants  operating  by  this  method  have 
been  erected  in  Rumania  and  elsewhere.  Edeleanu  gives 
a  full  description  of  the  working  method  in  "  Bulletin," 
Am.  Inst.  Min.  Eng.t  1914,  p.  2313. 

The  distillate  is  first  dried  by  passing  through  filters 
filled  with  dry  salt.  It  is  then  pumped  through  a  cold 
exchanger,  where  it  is  cooled  by  the  cold  extract  issuing 
from  the  mixing  vessel.  The  distillate  is  then  further  cooled 
by  passing  through  a  distillate  cooler,  where  it  is  cooled  by 
a  separate  refrigerating  system  (not  shown  in  the  diagram). 
It  then  passes  into  the  mixing  vessel,  where  it  meets  the 
liquid  sulphur  dioxide  which  has  likewise  been  cooled  by 


E«£ft2£.  j..^ 


FIG.  38. — Working  scheme  of  Edeleanu  plant. 

the  issuing  refined  product  and  in  a  special  cooler  by  means 
of  a  refrigerating  system  not  shown  in  the  diagram. 

As  the  sulphur  dioxide  is  admitted  into  the  mixer,  it  is 
at  first  completely  absorbed  by  the  distillate.  After  a  time, 
however,  the  mixture  separates  into  two  layers,  the  lower 
being  the  extract,  a  solution  of  the  aromatic  hydrocarbons  in 
liquid  sulphur  dioxide  ;  the  upper,  the  unaltered  naphthenes 
and  paraffins,  containing  some  sulphur  dioxide  in  solution, 
containing  also,  naturally,  some  proportion  of  aromatics 
unextracted,  according  to  the  conditions  of  working. 

The  extract  is  drawn  off  by  the  extract  pump  through 
the  distillate  cold  exchanger  to  the  extract  evaporator, 
where  it  is  heated  by  steam  coils  (not  shown  in  diagram)  ; 
the  sulphur  dioxide  is  returned  to  the  system  through 


TREATMENT  OF  PETROLEUM  OILS        207 

coolers  and  dryers,  and  the  extract,  now  free  from  sulphur 
dioxide,  is  pumped  away. 

The  refined  product  is  pumped  out  from  the  mixer 
through  a  cold  exchanger,  absorbing  heat  from  the  liquid 
sulphur  dioxide  in  this  case.  The  refined  product  then 
passes  on  to  its  evaporator,  where  the  dissolved  sulphur 
dioxide  is  driven  off.  The  heating  of  the  evaporators  may 
be  effected  by  the  exhaust  steam  from  the  engine  which 
drives  the  pumps  and  compressors.  Only  the  bare  outlines 
of  the  operation  of  the  plant  are  described  above. 

In  treating  a  Rumanian  distillate  of  sp.  gr.  0*820, 
75  per  cent,  of  a  refined  product  of  sp.  gr.  0*803,  an^ 
25  per  cent,  of  an  extract  of  0*869  were  obtained.  The  loss 
of  sulphur  dioxide  amounted  to  0*56  per  cent,  reckoned 
on  the  distillate  treated. 

The  oils  extracted  from  the  sulphur  dioxide  solution 
are  very  rich  in  aromatics  and  may  find  special  applications 
as  solvents  or  in  other  directions,  or  may  be  utilized  as  fuel, 
while  the  treated  kerosenes,  being  free  from  aromatic  hydro- 
carbons, are  of  excellent  quality  as  illuminating  oils  for  use 
with  the  ordinary  types  of  lamp  on  the  market. 


GENERAL  REFERENCES  TO   PART  VII.,   SECTION  C. 

Bacon  and  Hamor,  "  American  Petroleum  Industry."  McGraw  Hill 
Co. 

Campbell,  "  Petroleum  Refining."     C.  Griffin  and  Co. 

Ellis  and  Meigs,  "  Gasoline  and  other  Motor  Fuels."  D.  van  Nostrand 
Co. 


SECTION  D.— THE  MANUFACTURE   OF 
PARAFFIN   WAX  AND  LUBRICATING   OIL 

THE  starting  point  for  the  manufacture  of  paraffin  wax 
is  the  wax  distillate  obtained  by  the  distillation  of  paraffin 
wax-containing  crudes.  The  operation  of  the  subsequent 
processes  depends  to  a  very  great  extent  on  the  character 
of  this  distillate.  This  distillate  is  a  mixture  of  wax  and 
lubricating  oil  distillate,  and  both  wax  and  lubricating  oils 
are  made  therefrom.  Unfortunately  the  conditions  best  for 
lubricating  oil  production  are  not  those  best  for  wax  produc- 
tion, so  that  usually  a  compromise  must  be  made,  or  perhaps 
resort  may  be  had  to  redistillation.  The  less  steam  used  in 
distilling,  i.e.  the  higher  the  temperature  and  the  greater 
the  cracking,  the  more  easily  crystallizable  the  wax  and 
the  less  viscous  the  character  of  the  oil  and  vice  versa. 
The  extent  to  which  the  distillation  may  be  carried  is 
determined  almost  entirely  by  the  nature  of  the  crude  oil. 
Some  crude  oils  (e.g.  Pennsylvanian)  readily  give  up  their 
wax  on  distillation,  leaving  as  residue  an  oil  relatively 
wax  free.  vSuch  residues  may  indeed  be  used  as  "  steam 
refined  cylinder  stocks."  Others  leave  a  residue  which 
still  contains  much  wax.  This  residue  cannot  be  distilled 
further  by  the  ordinary  method  employing  steam,  as  the 
distillates  which  would  be  so  obtained  would  contain  high 
melting-point  wax  which  would  not  crystallize  or  sweat 
well,  perhaps  owing  to  the  highly  viscous  oil  with  which  it 
would  be  associated.  Such  residues  may  be  either  burnt 
as  fuel  or  distilled  by  the  so-called  cracking  distillation 
method,  i.e.  without  steam,  right  down  to  coke.  As  the 
paraffin  wax  existing  in  the  crude  oil  cannot  be  separated 

208 


THE  MANUFACTURE  OF  PARAFFIN   WAX  209 

off  by  means  of  filtration  owing  to  its  amorphous  condition 
the  oil  must  be  distilled.  The  paraffin  which  distils  over  is 
crystalline  and  amenable  to  filtration.  The  methods  adopted 
for  working  up  the  distillate  containing  paraffin  wax  vary 
with  different  crudes  and  in  different  refineries.  In  some 
cases  the  wax  distillates  are  subjected  to  a  sulphuric  acid 
treatment  and  perhaps  to  a  redistillation  before  being 
filtered,  but  in  many  cases  this  is  not  necessary. 

In  general,  the  method  of  extracting  the  wax  adopted 
is  that  of  filtering  off  the  wax  from  the  chilled  distillate, 
and  subsequently  freeing  it  from  oil  by  sweating,  or  by 
washing  by  solvents  which  dissolve  the  oil  but  not  the  wax, 
e.g.  alcohol. 

The  wax  distillate  is  "cut "  from  the  distillation  by  using 
the  congealing  point  as  a  guide,  the  points  selected  being 
based  on  previous  works  and  laboratory  experience  for  the 
particular  oil. 

The  chilling  of  the  distillates  may  be  effected  in  various 
types  of  plant.  That  in  general  use  in  the  United  States  is 
continuous  in  action,  viz.  the  "  Carbondale  "  type.  This  con- 
sists of  a  number  of  coolers  made  up  each  of  two  concentric 
pipes  arranged  one  over  the  other  horizontally.  The  wax 
distillate  is  pumped  through  the  internal  pipes,  each  of 
which  is  provided  with  a  worm,  passing  through  the  set  in 
series,  while  the  cold  brine  is  circulated  through  the  annular 
spaces  in  counter-current  fashion. 

The  cold  brine  is  produced  by  one  of  the  well-known 
types  of  refrigerating  plant,  usually  with  ammonia  as  working 
fluid.  For  details  of  the  operation  of  such  a  plant  the 
reader  must  be  referred  to  standard  works  on  refrigerating 
practice.  The  degree  to  which  the  wax  distillate  .is  cooled 
must  depend  on  its  wax  content.  If  the  wax  content  be 
high  the  operation  may  best  be  conducted  in  two  or  even 
three  stages.  In  such  a  case  the  chilled  distillate  would  be 
filtered,  and  the  filtered  oil  further  chilled  ;  if  the  chilling 
were  completely  effected  in  one  stage  the  chilled  distillate 
might  be  too  thick  to  handle. 

As  the  formation  of  well-defined  crystals  is  of  importance 

p.  14 


210    PETROLEUM  AND  ALLIED  INDUSTRIES 

because  of  the  subsequent  operations,  and  as  the  size  of 
the  crystals  depends,  not  only  on  the  material,  but  on  the 
conditions  of  cooling,  other  types  of  cooler  may  be  found 
more  satisfactory  in  certain  cases.  A  well-known  type  is 
the  "Henderson"  (Fig.  39).  This  is  composed  of  a  large 
rectangular  vessel,  which  may  have  a  capacity  of  10  tons  or 
more,  divided  up  into  a  number  of  narrow  compartments 
by  hollow  plates  through  which  the  cold  brine  circulates. 
A  central  shaft  carrying  scrapers  very  slowly  revolves, 
scraping  away  the  wax  as  it  crystallizes  on  the  surfaces  of 
the  hollow  plates.  A  stirrer  working  in  a  channel  along  the 
bottom  enables  the  pasty  mass  to  be  transferred  to  the 
suction  of  the  pump.  In  another  type  of  somewhat  similar 
design,  no  scrapers  are  employed,  so  that  the  cooling  is  very 
slow.  The  dividing  plates  are  in  this  case  made  tapering  in 
section,  so  as  to  allow  of  the  easy  removal  of  the  semi-solid 
mass. 

The  chilled  wax  distillate  is  then  passed  on  by  pumps 
to  the  filter-presses.  These  filter-presses  are  of  the  normal 
type,  sometimes  with  square  plates,  more  often  with  circular. 
The  presses  used  in  America  are  of  massive  construction — 
48  inches  in  diameter  with  300  plates.  These  presses  are  fitted 
with  hydraulic  ends  for  closing  the  press  tight,  as  pressures 
up  to  300  Ibs.  to  the  square  inch  are  sometimes  employed 
in  filtering  the  wax.  Numbers  of  these  presses  are  housed 
in  one  building,  which  must  be  kept  cool  and  well  insulated. 
It  is  usual  to  maintain  the  temperature  in  the  filter-presses 
a  degree  or  two  above  that  of  the  chilled  wax  distillate,  in 
order  to  ensure  that  no  crystallization  takes  place  in  the 
presses  (as  this  would  tend  to  clog  the  filter- cloths). 

When  any  one  press  is  full  and  has  been  pumped  up  to 
full  pressure,  the  supply  of  chilled  distillate  (which  may  be 
called  by  the  convenient  Galician  term  "  gatsch  ")  is  cut  off 
and  the  press  is  opened.  The  filter  cakes  fall  out  into  a 
conveyer  placed  beneath  the  press  and  are  conveyed  to  a 
melting-up  tank  outside  the  building. 

In  this  way  the  wax  distillate  is  separated  into  a  "  slack 
wax  "  filter  cake  and  filter  oil,  this  filter  oil  being  naturally 


THE   MANUFACTURE  OF  PARAFFIN   WAX  211 


212    PETROLEUM  AND  ALLIED  INDUSTRIES 

saturated  with  wax  at  the  temperature  of  filtration.  The 
slack  wax  may  amount  to  about  20  per  cent,  of  the  gatsch 
pumped  through  the  press. 

The  filter  oil  or  pressed  distillate,  if  from  a  first-stage 
chilling,  is  rechilled  and  refiltered,  thus  yielding  another 
batch  of  filter  cake  of  lower  melting  point ;  if  from  a  final 
chilling  it  is  reduced  or  concentrated  in  stills  to  the  required 
viscosity  to  yield  a  lubricating  oil. 

The  slack  wax  or  filter  cake  is  then  melted  up  and  pumped 
to  the  sweating  house,  where  it  is  subjected  to  the  sweating 
process. 

Sweating  is  a  process  of  fractional  melting.  The  opera- 
tion is  carried  out  in  sweating  pans,  erected  in  a  sweating 
house.  The  sweating  pans  are  shallow  sheet-iron  trays, 
5  or  6  inches  deep,  fitted  with  false  bottoms  of  coarse 
wire  gauze.  The  bottom  of  the  tray  slopes  from  all  sides 
toward  the  centre,  from  which  point  a  draw-off  pipe  leads 
to  a  main  draw-off  pipe,  passing  to  the  outside  of  the  house. 
Immediately  beneath  the  wire  gauze  false  bottoms  lie  a 
number  of  perforated  steam  pipes  and  just  above  the  gauze 
are  sometimes  fixed  a  number  of  f-inch  pipes,  through  which 
cooling  water  may  be  circulated. 

The  trays  are  first  partly  filled  with  water  covering 
the  gauze  false  bottoms.  Melted  slack  wax  is  then  floated 
on  to  the  surface  of  the  water  until  it  forms  a  layer  3  to  4 
inches  thick  and  is  then  allowed  to  cool.  When  the  wax  has 
solidified,  the  water  is  run  off,  the  cake  of  wax  being  thus 
allowed  to  rest  on  the  gauze  false  bottom. 

The  house,  containing  a  number  of  such  trays,  fitted  up 
one  above  the  other,  is  then  closed  up  and  slowly  warmed  by 
means  of  exhaust  steam  through  steam  pipes  placed  on  the 
walls.  As  the  temperature  rises,  sweating  starts,  the  oil 
oozes  out  of  the  fine  network  of  crystals,  accompanied  of 
course  by  much  low  melting-point  wax.  The  process  is 
controlled  by  watching  the  character  of  the  wax  flowing 
off  and  by  examining  the  product  as  it  lies  on  the 
trays. 

When  the  process  is  judged  to  be  complete,  the  wax 


THE  MANUFACTURE  OF  PARAFFIN  WAX  213 

lying  on  the  trays  being  oil-free  and  of  the  correct  melting 
point,  the  temperature  of  the  house  is  quickly  raised  and  live 
steam  is  blown  in  through  the  perforated  pipes,  so  that  the 
sweated  wax  on  the  trays  is  melted  up,  the  effluent  pipes 
being  then  diverted  to  the  sweated  wax  tanks. 

The  slack  wax  is  thus  split  up  into  sweated  wax  (which 
is  now  free  from  oil)  and  "  foots  oil "  and  "  foots  wax." 
The  "  foots  wax  "  is  resweated  to  yield  wax  of  lower  melting 
point,  or  it  may  be  in  part  returned  to  the  cool-house  or 
even  to  the  distilling  bench. 

The  process  of  sweating  is  slow,  usually  taking  from 
24  to  60  hours  according  to  the  nature  of  the  wax.  The 
above-described  apparatus,  which  is  that  in  most  genera;! 
use,  was  first  devised  by  Henderson  in  Scotland.  A  notice- 
able improvement  is  that  patented  by  Pijzel.  The  sweating 
stoves  are  made  movable  so  as  to  run  on  rails.  The 
sweating  house  consists  of  a  long  tunnel  heated  by  hot 
air,  with  a  melting-out  chamber  at  one  end.  The  sweating 
pans  enter  at  one  end  and  are  transferred  through  the  tunnel 
by  a  series  of  stages  as  each  finished  stove  is  melted  out. 
The  considerable  waste  of  heat  involved  in  alternately 
cooling  and  heating  the  sweating  house  is  thus  avoided. 

The  actual  control  of  the  operation  and  the  working 
details  depend  on  many  factors  and  must  be  worked  out  for 
each  particular  plant.  Generally,  several  grades  of  wax 
of  melting  points  say  about  122°,  127°,  132°,  and  140°  F. 
will  be  made  and  perhaps,  also,  a  very  soft  match-impreg- 
nating wax  too. 

The  sweated  wax  should  now  be  free  from  mineral  oil, 
but  will  still  contain  some  colouring  matter.  This  may  be 
removed  either  by  refining  or  by  filtration. 

If  the  refining  process  be  used  the  melted  paraffin  wax 
is  agitated  with  a  small  percentage  of  concentrated  sulphuric 
acid.  The  acid  sludge  is  drawn  off  and  the  melted  wax 
is  then  run  down  into  a  powder  mixer.  This  is  a  cylin- 
drical horizontal  vessel  fitted  with  paddles.  In  this  vessel 
the  wax,  kept  hot  by  means  of  steam  coils,  is  agitated 
with  a  decolorizing  powder,  such  as  animal  charcoal, 


214    PETROLEUM  AND  ALLIED  INDUSTRIES 

potassium  ferro-cyanide  waste,  some  type  of  fullers-earth  or 
bauxite. 

When  the  treatment  is  complete  the  whole  is  blown  by 
compressed  air  through  a  cloth  filter-press,  to  remove  the 
bulk  of  the  decolorizing  powder,  the  last  traces  being 
removed  by  filtering  through  paper  in  a  filter-press  fitted 
with  steam- jacketed  plates. 

Instead  of  treatment  with  acid  and  decolorizing  powder, 
a  filtration  treatment  may  be  adopted.  The  filter  used  is 
made  of  a  vertical  cylindrical  steam- jacketed  vessel,  which 
may  have  a  capacity  of  i  ton  or  more  of  filtering  medium. 
It  is  constructed  with  a  removable  bottom,  so  that  the 
exhausted  decolorizing  powder  may  be  removed.  The 
melted  wax  is  allowed  to  percolate  through  the  filtering 
medium,  which  may  be  a  fuller's-earth  such  as  floridin,  an 
animal  charcoal  or  bauxite  (Eng.  Pat.  16617  of  1908). 
The  filtering  medium  must  not  be  too  finely  divided,  other- 
wise filtration  is  too  slow.  It  is  usually  ground  to  the 
fineness  of  coarse  gunpowder.  In  some  cases  decolorizing 
powders  act  best  after  drying  at  105°  C.,  in  some  cases  best 
after  ignition.  This  point  must  be  settled  by  experiment  in 
the  laboratory.  As  the  wax  filters  through,  the  discolora- 
tion is  removed,  but  as  the  powder  loses  its  efficacy  the 
issuing  wax  will  begin  to  show  a  yellowish  tint.  At  a 
certain  point,  therefore,  the  filtration  must  be  stopped  and  the 
filter  drained.  The  exhausted  filtering  medium  is  then 
removed  and  a  fresh  charge  put  in.  After  filtration  the  wax 
is  finally  filtered  through  filter-presses  with  paper,  and  is 
then  run  off  into  moulds  and  allowed  to  cool.  It  may  also 
be  cooled  by  being  allowed  to  flow  in  a  thin  film  on  to  the 
surface  of  a  rotating  cylinder  cooled  internally  by  water, 
from  the  surface  of  wrhich  it  is  peeled  off  by  a  fixed  knife- 
edge  and  packed  directly  into  barrels. 

The  actual  details  of  the  method  to  be  employed  in 
working  up  any  particular  crude  for  wax  must  depend  upon 
the  crude  itself  and  upon  local  conditions. 

The  paraffin  wax  crudes  of  the  United  States  of  America, 
contain,  as  a  rule,  about  2  to  3  per  cent,  of  wax,  Galician  oils 


THE  MANUFACTURE  OF  PARAFFIN  WAX  215 

about  5  to  6  per  cent.,  while  some  of  the  oils  of  Burmah  and 
Borneo  contain  up  to  10  per  cent.,  or  more. 

As  an  example  the  following  scheme  of  working  up  a 
crude  oil  may  be  given  : — 

This  crude  yielded  on  distillation — 

Crude  benzine          . .         . .  14  per  cent. 

,,      kerosene        . .          . .  41        „ 

Gas  oil  3 

Wax  distillate          . .         . .  37       „ 
Coke  . .         ....         . .       3 

The  wax  distillate  was  worked  up  in  the  manner  set  out 
diagrammatically  below. 

WAX    D/5T/LL.ATC. 


/>O//VT-  */  c. 
ro~fo*c 


r 

eovcenTffinfo  at 


!j 

7-«0. 

C/i. 

r 

OffCC    SWCATCO 

I                                                    ! 

wJut.                                                                         AOO» 

WAX     JoX. 

tejLm. 
_l_ 

v/L    .c- 

x^^ 

1 

^^S, 

.i, 

"^*r™ 

LJ.v* 

FIG.  40.— Scheme  for  operating  a  wax  plant  making  one  grade  of  wax  only. 

This  represents  an  ideally  simple  case.  In  many  cases 
several  grades  of  wax  of  different  melting  points  are 
made. 

Variations  of  the  method  are  innumerable  and  must  be 


216    PETROLEUM  AND  ALLIED  INDUSTRIES 

worked  out  to  suit  each  case.  In  some  cases  the  foots  oil 
is  returned  to  the  cool-house  for  rechilling,  in  others  it  is 
redistilled,  in  some  cases  it  may  be  pumped  to  liquid  fuel. 
Paraffin  wax  is  also  extracted  from  materials  other  than 
crude  petroleums.  The  shale  oils  of  Scotland,  for  example, 
yield  about  2  per  cent,  of  rather  low  melting  point  (45/46°  C.) 
wax.  The  shale  oils  of  New  South  Wales  also  yield  paraffin 
wax,  as  do  in  general  most  shale  oils.  Tars  from  the  distilla- 
tion of  wood,  especially  beech,  also  yield  paraffin  wax ;  in 
fact,  this  is  the  material  from  which  paraffin  wax  was  first 
made.  Lignite  and  the  peculiar  mineral  substance  pyro- 
pissite  (vide  p.  151)  are  worked  up  in  Germany  and  yield 
considerable  quantities  of  paraffin  wax,  as  distinct  from 
the  montan  wax  already  alluded  to  (vide  p.  150).  As,  in 
the  case  of  such  tars  produced  by  distillation,  the  paraffin 
wax  exists  in  the  crystalline  form,  it  can  be  directl)7  separated 
from  the  tar,  topped  to  remove  the  lighter  fractions,  by  the 
usual  crystallizing  method. 

Several  processes  of  extracting  paraffin  wax  depending 
on  the  relative  solubilities  of  wax  and  mineral  oils  in  various 
solvents,  e.g.  alcohol  of  various  strengths,  acetone,  ethyl 
acetate,  etc.,  have  been  devised  (e.g.  German  Pats.  123101, 
140546,  and  149347),  but  these  methods  are  not  used  to 
any  extent.  Alcohol  will  dissolve  all  the  oils,  resins,  and 
creosotes  present  in  such  tars.  The  tar  is  dissolved  in  ten 
times  its  weight  of  90  per  cent,  alcohol  in  an  autoclave  at 
80°  C.  and  the  solution  cooled.  The  paraffin  wax  crystallizes 
out  and  may  be  separated  off  by  centrifuging. 

The  manufacture  of  lubricating  oil  is  intimately  con- 
nected with  that  of  paraffin  wax,  as  in  many  cases  lubricating 
oils  are  made  from  the  oils  resulting  from  the  filtering  off 
of  the  wax  from  wax  distillates.  Lubricating  oils  are  also 
manufactured  from  naphthenic  or  asphalt  base  oils,  in  which 
case  the  removal  of  wax  by  filtration  is  unnecessary. 

It  is  often  held,  though  by  no  means  proved,  that 
lubricating  oils  derived  from  paraffin  wax  base  oils  are 
of  better  quality  than  those  derived  from  naphthenic  or 
asphalt  base  crudes. 


MANUFACTURED  OF  LUBRICATING  OIL      217 

Lubricating  oils  may  be  divided  roughly  into  two 
classes,  residual  and  distillate  oils.  Residual  oils  are  those 
which  result  from  the  concentrating  down  by  distillation  of 
certain  types  of  crude  oil.  A  naphthenic  oil  free  from 
paraffin  and  not  rich  in  asphaltic  material  may  be  concen- 
trated down  to  make  a  low-grade  black  oil,  such  as  an 
axle  oil,  which  need  not  have  a  high  flash-point  or  good 
colour.  Such  oils  may  also  be  used  for  the  manufacture 
of  dark  greases. 

Certain  types  of  paraffin-wax-bearing  crude  oil  of  the 
Appalachian  fields  yield  as  a  residue  after  the  other  products, 
including  the  wax,  have  been  distilled  off,  a  so-called  "  steam- 
refined  cylinder  stock."  The  distillation  is  carefully  carried 
out  at  as  low  a  temperature  as  possible  (preferably  in  vacuo) 
with  ample  steam.  The  distillation  is  carried  on  until  the 
flash-point  of  the  residue  rises  to  from  500°  F.  to  700°  F. ; 
600°  F.  steam  refined  stock  being  the  grade  in  general  use. 
With  these  crudes  the  asphaltene  content  is  so  low  that 
these  residues,  which  have  exceptionally  high  flash-points, 
may  be  used  as  cylinder  oils  for  steam  cylinder  lubrication. 
With  other  types  of  crude  oils  the  residues  so  produced  would 
contain  too  much  wax,  or  be  too  rich  in  asphaltenes,  or  have 
too  low  a  flash-point,  and  so  be  of  relatively  inferior  quality. 
These  steam-refined  cylinder  stocks  may  be  filtered  through 
decolorizing  powders  or  animal  charcoal,  the  asphaltenes 
being  thus  removed,  so  that  a  fine-looking  oil,  reddish-brown 
by  transmitted,  green  by  reflected,  light  results.  Such 
oils  are  known  as  "filtered  cylinder  oils,"  and  are  much 
valued  as  such  and  for  blending  purposes.  Such  filtered 
cylinder  oils  may,  however,  still  contain  a  little  paraffin 
wax.  This  may  be  removed  by  dissolving  the  oil  in  light 
benzine,  chilling  the  mixture,  and  removing  the  separated 
wax  by  means  of  a  Sharpies  centrifugal  machine ;  the 
benzine  is  then  distilled  off  and  a  filtered  cylinder  bright 
stock  then  remains. 

Similar  cylinder  oils  may  be  manufactured  by  the 
concentration  of  lubricating  oil  distillates.  Russian  crudes, 
for  example,  may  be  distilled  down  to  "  astatki,"  or  thick 


218    PETROLEUM  AND  ALLIED  INDUSTRIES 

fuel  oil,  lubricating- oil  distillates  being  produced.  These 
lubricating-oil  distillates  may  be  concentrated  down  to 
cylinder  oils  of  flash-point  about  400°  F. 

This  concentration  is  carried  out  in  an  ordinary  fire- 
heated  still,  the  temperature  being  kept  down  as  low  as 
possible  by  means  of  copious  use  of  steam.  The  distilla- 
tion or  "  reducing  "  is  carried  on  until  the  tests  of  the  residue 
have  the  required  values.  This  reduction  is  best  effected 
in  vacuo,  the  quality  of  both  distillates  and  reduced  stock 
being  thus  improved. 

The  lighter  varieties  of  mineral  lubricating  oils  are  all 
distillates  which  may  or  may  not  have  been  reduced  to  grade 
by  concentration,  or  which  may  be  straight  distillates,  or 
perhaps  blends  of  several  distillates. 

The  material  used  may  be  either  a  distillate  from  riaph- 
thene  base  crude  oils,  such  as  those  of  Russia,  Texas,  and 
California,  or  a  filtered  "  press  oil  "  obtained  by  filtering 
off  the  paraffin  wax  from  a  well-cooled  wax  distillate  obtained 
from  wax  or  mixed  base  crude  oils,  e.g.  certain  of  those  of 
Pennsylvania  or  Mid-continent  fields. 

When  the  distillates  have  been  distilled  or  concentrated 
to  the  required  viscosity,  they  must  be  refined.  In  some 
cases  these  oils  are  refined  before  pressing  out  the  wax,  in 
other  cases  the  refining  is  the  last  treatment  to  which  they 
are  subjected. 

In  United  States  practice  the  lighter  wax  distillates  are 
called  "  neutral  oils  "  or  "  spindle  distillates." 

The  pressed  distillate  after  reducing  to  grade  is  filtered 
through  a  decolorizing  medium,  and  does  not  receive  an 
acid  treatment.  The  resulting  oil  is  termed  a  "  neutral 
oil."  Such  neutral  oils  may  be  termed  "  non- viscous  "  or 
"  viscous  "  according  to  their  viscosity. 

The  chemical  treatment  of  lubricating  oil  by  means 
of  sulphuric  acid  is  carried  out  in  agitators  of  the  usual  type, 
the  temperature  of  the  oil  being  kept  as  low  as  conveniently 
possible  in  regard  to  fluidity. 

In  order  to  economize  plant  the  settling  out  of  the 
acid  sludge  is  usually  allowed  to  take  place  slowly  in  shallow 


MANUFACTURE  OF  LUBRICATING  OIL     219 

settling  tanks  of  large  diameter.  When  the  acid  sludge  has 
settled  out  completely  the  oil  is  transferred  to  the  soda 
agitators,  where  it  is  gently  warmed  and  neutralized  with 
caustic  soda,  being  subsequently  well  washed  by  sprays  of 
water,  and  finally  dried  by  the  blowing  through  of  air.  The 
process  of  refining  of  lubricating  oils,  particularly  the 
neutralizing  and  washing,  is  difficult,  as  emulsions  often 
form  with  great  readiness,  and  these  may  be  difficult  to 
split  up. 

The  splitting  of  such  emulsions  is  usually  effected  by 
the  addition  of  dilute  acid,  and  subsequent  re-treatment 
by  soda  after  good  settling  out  of  the  dilute  acid  layer. 
The  addition  of  small  quantities  of  oleic  acid  during  the  soda 
treatment  may  also  assist  in  preventing  the  emulsification, 
and  the  addition  of  salt  water  may  sometimes  break  up  an 
emulsion  once  formed. 

Sodium  silicate  in  a  solution  of  specific  gravity  about 
30  Be.  may  also  be  used  in  place  of  soda,  the  precipi- 
tated silica  perhaps  assisting  by  carrying  down  impurities 
mechanically. 

Many  other  methods  of  refining  have  been  proposed 
for  which  vide  Engler-Hofer,  "  Das  Erdol,"  vol.  3,  pp.  522, 

527. 

No  general  rules  can  be  laid  down,  as  the  detailed  method 
of  treatment  of  any  oil  depends  on  the  nature  of  the  oil. 
The  losses  incurred  by  refining  in  this  way  are  high, 
amounting  to  as  much  as  20  per  cent,  or  more  in  particular 
cases. 

As  the  general  plan  of  the  working  up  of  a  shale  oil  into 
wax  and  lubricating  oils  may  be  more  complicated  than  that 
of  a  petroleum  crude,  a  scheme  of  working  up  a  Scotch  shale 
oil  (vide  "  The  Oil  Shales  of  the  Lothians,"  Mem.  Geol. 
Survey,  Scotland)  is  herewith  given  : — 


220  PETROLEUM  AND  ALLIED  INDUSTRIES 


ctf  <i> 

a  .22 

VH 


4)    C} 

O 


41 


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-?l 


T3 

1 

-S- 


1« 


o 


.a 


rt  o 

Si  o 

"    O 


.•3  —  —  a 
S 
a 


I 


"ri'2 

l§ 


^ 
o  r^-5 

c  ° 


MANUFACTURE  OF  LUBRICATING  OIL     221 

It  must  be  again  emphasized,  however,  that  every  oil 
to  be  worked  up  must  be  treated  on  its  own  merits,  and 
the  best  method  for  that  particular  case  must  be  devised. 

The  various  grades  of  mineral  lubricating  oil  made  and 
their  properties  will  be  described  under  the  section  dealing 
with  applications  of  petroleum  products. 

"Perotlatum,"  also  known  as  petroleum  jelly,  petroleum 
ointment  and  vaseline  (the  trade  name  of  the  well-known 
product  made  by  the  Cheeseborough  Co.),  is  a  product 
defined  in  the  United  vStates  pharmacopoeia  as  "  a  mixture 
of  hydrocarbons  chiefly  of  the  methane  series  obtained  by 
distilling  off  the  lighter  and  more  volatile  portions  from 
petroleum  and  filtering  the  residue." 

It  may  be  prepared  from  the  residues  from  the  distilla- 
tion of  certain  paraffin  wax  base  crude  petroleums,  the 
concentration  being  carried  to  the  necessary  extent.  Many 
paraffin-rich  crudes  will,  however,  not  yield  a  suitable 
product.  It  may  also  be  made  from  the  "  rod  wax  "  which 
accumulates  in  the  pumps  of  certain  wax  crude  wells  (Mabery, 
Proc.  Am.  Acad.,  1904,  p.  349),  and  from  the  bottom  settlings 
(B.S.)  of  the  same  type  of  oil. 

The  residues  or  "  reduced  oils  "  from  certain  cnides  are 
filtered  through  animal  charcoal  or  some  form  of  fuller's- 
earth  in  steam-jacketed  filters,  the  first  runnings  being 
collected  and  steamed  to  remove  any  earthy  smell  due  to 
the  fuller 's-earth.  The  rod  wax  or  crude  oil  B.S.  may 
be  similarly  distilled  to  the  right  concentration  and  then 
filtered. 

Another  variety  of  petrolatum  is  made  by  the  addition 
of  paraffin  wax  of  low  melting  point  to  lubricating  oils 
filtered  to  a  fine  colour.  Such  petrolatums  are,  however, 
not  so  homogeneous  and  separate  out  crystalline  paraffin. 

Liquid  Petroleum  or  Medicinal  Oil  is  a  product 
which  is  to  all  intents  and  purposes  a  highly  refined  lubri- 
cating oil.  Oil  of  a  suitable  viscosity  is  treated  with  suc- 
cessive treatments  of  oleum,  neutralized  and  filtered  through 
f uller's-earth.  The  treatment  is  very  drastic  and  the  refining 
losses  very  heavy.  The  product  is  quite  odourless,  tasteless, 


222    PETROLEUM  AND  ALLIED  INDUSTRIES 

and  colourless.  The  hydrocarbons  which  are  present  in 
petrolatums  are  all  undoubtedly  of  a  saturated  type.  In 
the  types  of  petroleum  derived  from  residue  no  crystalline 
hydrocarbons  are  present,  the  solid  members  being  probably 
similar  to  those  found  in  ozokerite  or  natural  mineral  wax. 

Lubricating  Greases. — These  are  made  in  great 
variety,  a  petroleum  oil  forming  the  basis  of  the  majority. 
They  are  composed  in  the  main  of  two  constituents,  a  soap 
and  an  oil,  the  soap  usually  being  formed  during  the  manu- 
facture of  the  grease.  Calcium  and  sodium  soaps  are 
generally  used,  but  certain  greases  contain  potassium  and 
aluminium  soaps.  Moreover,  some  greases  contain  fillers 
such  as  graphite,  French  chalk,  mica,  etc.  Many  varieties 
of  oils  and  fats  are  used,  such  as  palm  oil,  tallow,  resin  oil, 
anthracene  oil,  and  petroleum  residual  oils. 

The  plant  used  for  the  manufacture  of  greases  is  simple, 
consisting  merely  of  (a)  a  melting  and  boiling  pot  for  melting 
up  or  heating  the  fat  or  oil,  (b)  a  mixing  vessel  with  steam- 
jacketed  walls  and  arrangements  for  stirring.  The  con- 
stituents of  the  grease  are  introduced  into  the  boiling  pot 
and  heated  for  several  hours,  the  contents  then  being  run 
down  into  the  mixing  vessel,  where  they  are  thoroughly 
incorporated.  Fats  proper  or  fatty  acids  may  be  used  for 
grease  making,  in  the  former  case  the  glycerin  remaining 
in  the  grease. 

A  cup  or  motor  grease  may  be  made  by  the  incorporation 
of  about  6  per  cent,  of  hard  tallow  soap  into  an  engine  oil, 
or  alternately  by  boiling  up  tallow,  and  finely  divided  slaked 
lime  free  from  grit  with  the  necessary  proportions  of  the 
selected  mineral  lubricating  oil. 

The  so-called  4<  fibre  greases  "  are  made  by  using  caustic 
soda  in  place  of  lime.  "  Rosin  greases  "  are  made  by  boiling 
lime  with  rosin  oils  ;  "  black  greases  "  by  the  use  of  mineral 
residual  oils.  A  product  termed  "  mineral  castor  oil,"  which 
contains  an  aluminium  soap,  is  used  for  the  lubrication  of 
agricultural  machinery.  A  soap  stock  is  made  by  making  first 
a  sodium  soap  and  treating  this  with  alum  solution.  The 
aluminium  soap  is  then  dissolved  in  a  quantity  of  mineral  oil 


MANUFACTURE  OF  LUBRICATING  OIL     223 

and  the  clear  soap  stock  so  obtained  is  mixed  into  further 
quantities  of  mineral  lubricating  oil  to  make  the  various 
grades  of  "  mineral  castor  "  required.  Innumerable  types  of 
greases  are  manufactured  and  sold ;  an  enumeration  of  the 
various  formulae  used  for  compounding  would  serve  no  good 
purpose  here. 

Cutting  Oils. — A  special  product  which  should  have  good 
lubricating  properties  and  a  high  specific  heat  is  required 
for  lubricating  cutting  and  drilling  tools,  as  an  important 
function  of  such  a  lubricant  is  the  cooling  of  the  cutting 
edge.  The  so-called  water  soluble  oils  are,  therefore,  largely 
used  for  this  purpose.  Water  soluble  oils  are  usually 
mineral  oils  held  in  suspension  by  soaps,  alkalies,  or  sulphon- 
ated  oils.  These  oils  should  be  readily  miscible  and  form  a 
stable  emulsion  with  water  so  that  they  may  be  circulated 
and  used  over  and  over  again. 

Oleic  acid  is  saponified  with  soda,  the  solution  concen- 
trated and  mixed  with  alcohol,  and  then  with  a  mineral 
oil.  The  naphthenic  acids  extracted  during  the  refining 
of  mineral  oils  may  be  used  for  the  purpose  of  making  the 
soaps  for  these  soluble  oils.  Sulphonated  castor  oils  are 
also  used  for  this  purpose. 


GENERAL   REFERENCES  TO   PART  VII.,   SECTION  D. 

Bacon  and  Hamor,  "  The  American  Petroleum  Industry,"  vol.  2. 
McGraw  Hill  Publishing  Co. 

Battle,  "  Industrial  Oil  Engineering,"  vol.  I.     C.  Griffin  and  Co. 

Campbell  and  Wilson,  J.I.P.T.,  1919,  p.  106. 

Engler-Hofer,  "  Das  Erdol,"  vol.  3.     Hirzel,  Leipzig. 

Gregorius,  "  Mineral  Waxes."     Scott,  Greenwood  and  Co. 

Hurst,  "  Lubricating  Oils,  Fats,  and  Greases."  Scott,  Greenwood 
and  Co. 


SECTION  E.—  THE  MANUFACTURE  OF  FUEL 
OILS,  RESIDUAL  OILS,  AND  ASPHALTS 
FROM  CRUDE  PETROLEUMS 

THE  manufacture  of  fuel  oils  from  various  crudes  is  a 
comparatively  simple  operation,  the  modus  operandi  depend- 
ing on  the  nature  of  the  crude  oil  and  the  type  of  fuel  oil  to 
be  produced.  There  are  a  number  of  crude  oils,  particularly 
of  the  naphthene  base  type,  which  yield  a  residual  fuel  oil, 
of  low  viscosity  after  the  distillation  off  of  the  benzine  and 
kerosene  fractions. 

Such  fuel  oils  may  be  of  low  cold  test,  liquid  at  tem- 
peratures well  below  o°  C.  These  oils  easily  fulfil  the 
conditions  of  the  British  Admiralty  specification  and  may 
in  many  cases  be  used  as  diesel  oils  even  for  marine 
engines. 

Crude  oils  of  other  types  which  contain  asphalt  in  greater 
quantity  yield,  as  a  residue  after  distillation  off  of  the 
benzine  and  kerosene  fractions,  a  fuel  oil  of  greater  viscosity 
and  higher  cold  test.  Such  an  oil,  while  a  perfectly  satis- 
factory fuel,  may  not  conform  to  Admiralty  specification. 
Other  crudes,  e.g.  the  asphaltic  crudes  of  Mexico,  after  only 
the  benzine  fractions  have  been  topped  off,  yield  a  residue 
which  is  too  viscous  for  use  as  fuel  without  special  heating 
and  burning  arrangements.  Such  crude  oils  are,  however, 
valuable  as  sources  of  asphalt. 

In  distilling  such  crudes  down  to  asphalts  of  the  required 
specification,  quantities  of  gas  oil  distillate  are  obtained, 
which  distillate  may  be  used  directly  as  a  diesel  fuel  oil,  or 
as  a  diluent  for  thinning  down  supplies  of  a  too  thick  fuel 
oil.  Other  types  of  crude  oil  yield  a  wax  residue  which  may 
be  distilled  to  coke  in  a  coking  still,  yielding  wax  distillate 

224 


THE  MANUFACTURE  OF  FUEL   OILS       225 

and  wax  tailings,  which,  on  filtration,  yield  an  oil  which  may 
be  used  as  fuel. 

Fuel  oils  may  thus  be  divided  into  two  categories — 
(a)  distilled  fuel  oils,  i.e.  gas  or  solar  oils,  which  being 
distillates  are  free  from  any  residual  asphalt,  and  which 
therefore  form  high-class  oils  for  diesel  and  semi-diesel 
engines,  and  which  may  be  used  as  a  basic  material  for 
cracking — either  to  gas  for  enriching  illuminating  gas,  or  to 
motor  spirits  (vide  Section  F) ;  and  (b)  residual  fuel  oils 
which  may  be  used  for  diesel  engine  fuels  in  some  cases,  and 
as  furnace  oils  in  all  cases. 

Of  similar  nature  are  the  residual  oils  used  for  road 
spraying  (road  oils),  and  those  used  for  thinning  down 
asphalts  (flux  oils),  which  are  merely  residual  oils  which 
must  conform  to  certain  specifications  as  regards  viscosity, 
flash-point,  etc.,  and  which,  therefore,  must  be  made  from 
certain  selected  crudes.  The  manufacture  of  all  such  oils 
may  be  carried  out  in  the  ordinary  type  of  still,  or  in  a 
plant  of  the  tubular  retort  type,  it  being  merely  a  question 
of  distilling  off  sufficient  distillate  to  obtain  a  residue  of  the 
required  character. 

Asphalts  are  manufactured  from  certain  types  of  crude 
oil  which  contain  little  or  no  paraifin  wax.  Certain  crudes 
which  are  free  from  wax  contain,  however,  little  asphalt, 
and  may  thus  best  be  used  for  liquid  fuel  manufacture. 
Most  native  asphalts  are  much  too  hard  for  most  purposes, 
particularly  for  road  work,  and  so  must  be  softened  by  the 
addition  of  flux  oil.  Asphalts  made  from  certain  types  of 
crude  petroleum  can,  however,  be  made  to  any  degree  of 
hardness  by  controlling  the  distilling  process. 

The  best  asphalts  are  produced  from  certain  crude  oils 
of  Mexico  and  California.  Certain  crudes  of  Texas, 
Venezuela,  Trinidad,  and  elsewhere  also  yield  good  asphalts. 

The  process  of  manufacture  consists  in  distilling  down 
to  the  required  concentration  under  certain  conditions. 
To  obtain  the  best  qualities  of  asphalt,  the  avoiding  of 
cracking  is  necessary ;  consequently  distillation  to  asphalt 
is  always  carried  out  with  the  assistance  of  copious  supplies 
P.  15 


226    PETROLEUM  AND  ALLIED  INDUSTRIES 

of  steam  blown  into  the  still  during  distillation,  the  distilling 
temperature  being  kept  thus  as  low  as  possible. 

This  distillation  is  usually  conducted  in  very  large  stills; 
worked  periodically ;  it  may  also  be  carried  out  in  a  con- 
tinuous bench  of  stills,  the  control  being  effected  by 
examination  of  the  residue  rather  than '  of  the  distillate. 
The  distillates  may  be  gas  or  lubricating  oils,  according  to 
the  grade  of  asphalt  which  is  being  made.  An  objection  to 
this  mode  of  distillation  is  the  length  of  time  to  which  the 
asphalt  is  subjected  to  a  high  temperature. 

It  may  also  be  made  by  one  of  the  topping-plant  type  of 
tubular  stills.  In  this  case  the  asphalt  is  subjected  to  the 
necessary  temperature  for  distillation  for  a  very  much 
shorter  period.  Overheating  of  an  asphalt  during  manu- 
facture is  indicated  by  the  difference  in  solubility  in  carbon 
bisulphide  and  carbon  tetrachloride.  This  difference  for  a 
well-made  asphalt  should  not  exceed  0-5  per  cent. 

The  temperature  of  distillation  may  also  be  kept  down 
by  distilling  in  a  high  vacuum  plant,  a  method  which  produces 
asphalts  of  very  good  quality. 

The  grade  of  asphalt  is  usually  defined  by  the  penetration 
test,  i.e.  the  depth  to  which  a  standard  needle  (No.  2  sewing 
needle)  under  a  load  of  100  grammes  will  sink  into  the  asphalt 
at  a  definite  temperature  (77°  F.)  in  5  seconds.  Grades  of 
penetration  varying  from  200  to  40  are  usually  made  for 
road  work.  Harder  asphalts  are  also  sometimes  made  for 
certain  purposes. 

Blown  Asphalts. — I/arge  quantities  of  asphalt  are  also 
made  by  the  blowing  process.  As  far  back  as  1865  it  was 
known  that  asphaltic  substances  were  susceptible  to  the 
action  of  oxidizing  agents,  which  produced  products  of 
greater  viscosity.  In  1894  a  patent  was  granted  to  Byerley 
for  "  blowing  "  petroleum  residual  oils  by  means  of  air. 
The  action  which  takes  place  appears  to  be  a  condensation, 
hydrogen  being  removed  from  two  molecules  as  water,  the 
molecules  then  condensing  up. 

The  blowing  process  is  carried  out  in  large  stills,  the 
larger,  the  easier  the  control.  The  oil  or  asphalt  to  be 


THE  MANUFACTURE  OF  ASPHALTS        227 

blown  is  heated  up  to  a  temperature  between  200°  and 
230°  C.  Copious  supplies  of  air  are  introduced  by 
means  of  a  large  number  of  perforated  pipes  placed  in  the 
bottom  of  the  still.  As  the  oxidation  proceeds,  sufficient 
heat  is  developed  to  render  external  heating  necessary  ; 
indeed,  care  must  be  exercised  to  prevent  the  temperature 
rising  too  high.  As  the  oxidation  proceeds  the  melting 
point  of  the  asphalt  rises,  the  penetration  decreases,  and 
the  ductility  falls  off  very  rapidly.  In  this  way  heavy  road 
oils  or  liquid  asphalts  may  be  blown  to  asphalts  of  high 
melting  point.  These  asphalts,  if  produced  from  a 
moderately  hard  asphalt  to  start  with,  may  be  brittle  and 
hard ;  if  produced  from  a  liquid  asphalt  containing  much 
oil,  may  be  tough,  pliable,  and  leathery  in  nature.  The 
qualit}'  of  the  blown  asphalt  may  thus  be  varied  considerably 
by  varying  the  basic  material,  and  to  some  extent  also  by 
varying  the  conditions  of  blowing. 

During  the  blowing  process,  vapours  are  given  off  which 
may  be  condensed  and  used  as  fuel  oil. 

The  blowing  process  has  several  advantages  : — 

(1)  The  yield  of  asphalt  from  a  given  petroleum  residual 
oil  is  greater  than  that  obtained  by  distillation  methods. 

(2)  Certain  crudes  which  would  yield  little  or  no  asphalt 
by  distillation  will  yield  asphalts  of  good  quality  by  blowing. 
Naturally,  the  more  asphaltic  the  nature  of  the  crude  the 
less  blowing  necessary. 

(3)  Blown  Asphalts  are  less  susceptible  to  temperature 
changes  than  are  those  made  by  distillation.     The  process, 
however,  is  of  longer  duration.     Much  care  must  be  taken 
in  the  manufacture  of  blown  asphalts,  particularly  when  they 
are  made  from  crudes  poor  in  asphalt.     When  made  from 
mixed  base  petroleums  they  are  likely  to  present  a  greasy 
surface,  owing  to  the  presence  of  paraffin  wax.     In  general, 
blown  asphalts  are  characterized  by  lack  of  ductility,  and 
if  overblown,  or  blown  at  too  high  a  temperature,  they  will 
contain   excess   of   carbenes   and   even   free   carbon.    The 
fusing  point  of  a  blown  asphalt  will  generally  be  found  to  be 
higher  than  that  of  a  residual  asphalt  of  the  same  penetra- 


228    PETROLEUM  AND  ALLIED  INDUSTRIES 

tion.  The  subject  of  blown  asphalts  is  treated  in  detail  in 
Abrahams'  book  on  "Asphalts  and  Allied  Substances/' 
p.  287  (D.  van  Nostrand  Co.). 

Vulcanized  or  Sulphurized  Asphalts  may  be  made  by 
treating  with  sulphur,  the  sulphur  apparently  affecting  the 
condensation  (with  liberation  of  sulphuretted  hydrogen) 
just  as  does  oxygen.  The  product  is  similar  in  character  to 
an  air-blown  asphalt. 

Sludge  asphalts  may  be  obtained  from  the  sludge  acids 
resulting  from  the  treatment  of  kerosenes  and  lubricating 
oils.  These  sludges  are  boiled  with  water  until  all  the  acid 
separates  and  leaves  a  heavy  residuum.  This  is  then 
washed  with  water  and  heated  to  the  required  consistency 
by  the  injection  of  superheated  steam.  Sludge  asphalts  are 
characterized  by  a  high  content  of  sulphur  and  oxygen,  and 
high  solubility  in  aromatic  free  petroleum  spirit  (sp.  gr. 
0*645).  They  do  not  withstand  the  weather  as  well  as  do 
the  blown  and  residual  asphalts,  and  are  at  present  of 
comparatively  little  importance. 

There  are  many  other  varieties  of  asphalt  of  minor 
importance,  such  as  wurtzilite  asphalt  or  kapak,  which  is 
made  by  the  distillation  of  wurtzilite  under  pressure.  This 
is  characterized  by  high  melting  point  and  great  toughness, 
being  somewhat  similar  to  blown  asphalts. 

A  great  variety  of  somewhat  similar  bodies,  properly 
termed  "  pitches,"  are  manufactured  by  the  distillation  of 
such  substances  as  stearine,  cotton  seed,  wool  grease,  etc., 
being  obtained  as  by-products  from  the  refining  of  vegetable 
oils  and  greases,  etc.,  a  description  of  which  lies  beyond  the 
scope  of  this  book. 


GENERAL   REFERENCES   TO   PART   VII.,    SECTION   E. 

Abrahams,  "  Asphalts  and  Allied  Substances."     D.  van  Nostrand  Co. 
Kohler  and  Graefe,  "  Natiirliche  und  kiinstliche  Asphalte."     Vieweg 
und  Sohn. 


SECTION  F.— CRACKING  AND  HYDRO- 
GENATING  PROCESSES 

THE  extraordinary  rapid  growth  of  the  automobile  industry 
has  given  rise  to  a  constantly  increasing  demand  for  benzine, 
which,  so  far,  has  been  met  by  the  petroleum  industry. 
The  motor  spirit  of  twenty  years  ago  consisted  almost 
entirely  of  the  most  volatile  fractions  of  crude  oil.  Products 
boiling  completely  below  120°  C.  were  common.  As  the 
demand  increased,  and  as  carburettors  were  improved,  the 
volatility  of  the  benzine  decreased.  In  consequence  of  the 
great  demand  present-day  motor  spirits  are  much  less 
volatile  and  include  fractions  of  higher  boiling  point.  Final 
boiling  points  of  220°  C.  are  not  uncommon ;  indeed,  in  the 
United  States  of  America  benzines  of  final  boiling  point 
230°  C.,  or  even  higher,  are  on  the  market. 

It  has  long  been  realized  that,  by  the  ordinary  means  of 
distillation,  a  sufficient  yield  of  benzine  cannot  possibly  be 
obtained  in  the  future  from  the  available  supplies  of  crude 
oils.  Efforts  have  consequently  been  made  to  increase 
the  yield  by  resort  to  cracking  methods,  i.e.  methods  of 
converting  hydrocarbons  of  high  boiling  point  into  those  of 
low  boiling  point. 

As  far  back  as  1861  an  American  stillman  accidentally 
noticed  that  high  boiling-point  hydrocarbons,  at  high 
temperatures,  e.g.  when  distilling  without  steam,  cracked, 
yielding  hydrocarbons  of  lower  boiling  point.  In  1863 
Breitenlohner  passed  the  vapours  of  heavy  mineral  oils 
through  red-hot  tubes,  obtaining  volatile  oils,  hydrogen, 
and  coke.  In  1865  Young  took  out  a  patent  (Eng.  Pat, 
3345  of  1865)  for  increasing  the  yield  of  burning  oil  by 
distilling  under  pressure.  In  1866  Vincent,  Richards  and 

229 


230     PETROLEUM  AND   ALLIED  INDUSTRIES 

others  (Eng.  Pat.  616  of  1866)  patented  a  process  by  which 
the  vapours  partly  condensed  and  dropped  back  into  the 
hot  residue,  thus  facilitating  cracking.  In  1871  Thorpe 
and  Young  (Proc.  Roy.  Soc.,  vol.  19,  p.  370,  vol.  20,  p.  488, 
vol.  21,  p.  184)  described  the  formation  of  hydrocarbons 
of  the  paraffin  and  olefme  series,  by  heating  paraffin  wax 
under  pressure.  In  1889  Redwood  and  Dewar  (Eng.  Pat. 
10277  °*  1889,  13016  of  1890,  5971  of  1891)  patented  a 
process  for  cracking  by  distilling  and  condensing  the  vapours 
under  pressure. 

Since  that  time,  hundreds,  even  thousands,  of  patents 
have  been  granted  for  cracking  processes  of  one  kind  or 
another,  a  fact  which  indicates  the  importance  of  the 
subject.  The  fact  that  up  to  the  present  no  really  satis- 
factory cracking  process  has  been  devised  indicates  the 
difficulty  of  the  problem. 

The  theoretical  side  of  the  subject  has  been  by  no  means 
completely  investigated.  The  factors  influencing  the  crack- 
ing of  any  particular  heavy  oil  must  be  numerous,  and  their 
study  complicated  by  the  difficulty  of  getting  any  informa- 
tion as  to  the  chemical  nature  of  hydrocarbons  of  high 
boiling  point.  The  number  of  bodies  taking  part  in  the 
reaction  may  be  great,  as  also  the  number  of  bodies 
formed. 

In  general,  cracking  may  be  said  to  be  a  splitting  up  of 
complex  molecules,  or  a  reaction  between  complex  molecules, 
of  such  a  nature  that  simpler  molecules  and  also  more 
complex  molecules  are  formed.  As  the  percentage  of 
hydrogen  in  the  molecules  of  low  molecular  weight  is  higher 
than  in  the  molecules  of  high  molecular  weight,  the  forma- 
tion of  low  molecular  weight  molecules  must  be  accompanied 
either  by  liberation  of  carbon,  or  by  formation  of  molecules 
of  higher  molecular  weight. 

The  chief  difficulty  in  most  cracking  processes  is  indeed 
the  separating  out  of  solid  carbon  which  clogs  up  the  plant. 
It  is  quite  open  to  doubt  how  far  this  material  is  really 
carbon,  how  far  it  is  really  composed  of  carbon  compounds 
of  high  molecular  weight. 


CRACKING  PROCESSES  231 

The  reactions  are  further  complicated  by  the  fact  that 
unsaturated  hydrocarbons  and  even  hydrogen  are  often 
formed.  The  temperature  at  which  noticeable  cracking 
takes  place  depends  on  the  nature  of  the  oil,  and  the  influence 
of  the  temperature  on  the  rate  of  cracking  is  very  marked. 

F.  W.  Padgett  (Chem.  and  Met.  Eng.,  1920,  p.  521) 
gives  the  following  data  showing  the  influence  of  tempera- 
ture on  the  cracking  of  paraffin  wax  : — 

Temperature  in  still  in  °  C.            . .     417  432  437 

Illuminating  oil  produced  %         . .       25*4  37*0  33-5 

Hydrogen  produced  %       . .         . .         0*3        0*9  3*0 

Saturated  hydrocarbons  produced  %    74*3  62*1  63*5 

By  slight  changes  in  the  working  temperature  the 
character  of  the  cracking  may  be  considerably  altered. 
Standinger,  Endle,  and  Herold  (Ber.,  46,  p.  2466),  and 
Zanetti  (J.  Ind.  and  Eng.  Chem.,  vol.  8,  p.  20)  among  others, 
investigated  the  effect  of  temperature  in  the  case  of  particular 
hydrocarbons.  As  a  general  rule  it  may  be  taken  that 
(i)  temperatures  up  to  500-600°  C.  yield  chiefly  mixtures  of 
paraffins  and  olefines;  (2)  temperatures  about  700°  C.  yield 
defines,  diolefines,  and  aromatic  hydrocarbons  with  smaller 
quantities  of  paraffins ;  (3)  temperatures  about  1000°  C. 
yield  permanent  gases  and  heavy  oils  rich  in  aromatic 
hydrocarbons. 

Pressure  is  another  important  factor,  the  general  effect 
of  pressure  being  to  enable  reactions  to  take  place  at  lower 
temperatures,  especially  reactions  of  the  nature  of  polymeri- 
zation. 

As  a  general  rule  the  unsaturated  hydrocarbons  and  the 
paraffins  are  least  stable  towards  heat,  the  aromatics  most 
so.  Padgett  (loc.  cii.}  suggests  the  following  t}^pe  reactions: — 

(1)  R-CH2-CH2-CH2-R->R-CH=CH-CH3+RH 

(2)  R-CH2-CH2-CH3->RH+CH2=CH2+C+H2 

(3)  R-CH2-CH2-R->RCH3+C+RH 

As  olefines  doubtless  occur  in  many  crudes,  particularly 


232    PETROLEUM  AND  ALLIED  INDUSTRIES 

in  the  fractions  of  high  boiling  point,  the  following  type  of 
reaction  may  occur  : — 

(4)  R-CH=CH2->RCH3+C. 

Olefines  may  also  crack  in  this  way — 

R-CH2-CH2-CH=CH-RH>RCH=CH-CH=CH2+RH 
yielding  diolefines,  a  class  of  hydrocarbons  which  are 
certainly  present  in  many  cracked  distillates. 

Further,  at  high  temperatures  particular  reactions  which 
give  rise  to  the  formation  of  aromatic  hydrocarbons  take 
place,  as  exemplified  in  the  cracking  processes  of  Hall  and 
of  Rittman. 

The  real  problem  awaiting  solution  is  the  conversion  of 
heavy  asphaltic  residues  into  volatile  products.  So  far 
only  the  cracking  of  heavy  distillates,  such  as  gas  oil,  has 
met  with  any  measure  of  commercial  success.  The  forma- 
tion of  coke  when  cracking  such  a  distillate  is  naturally  less 
than  would  be  the  case  if  a  residue  were  cracked. 

The  chief  difficulty  in  the  way  of  commercial  cracking 
is  this  formation  of  coke.  The  coke  deposits  on  some  part 
of  the  surface  through  which  the  heat  is  transmitted  to  the 
oil,  and  this  gives  rise  to  overheating  of  the  metal  in  this 
place,  with  its  consequent  burning  through.  Should  this 
happen  in  the  case  of  a  plant  under  pressure  a  disastrous 
accident  may  ensue. 

Cracking  processes  may  be  divided  into  the  following 
classes : — 

(a)  Distillation  without  steam  at  ordinary  pressures. 

(b)  Distillation  or  heating  under  pressure. 

(c)  Heating  the  oil  in  the  vapour  phase. 

(d)  Hydrogenating  methods. 

(e)  Various  other  methods. 

(a)  A  mild  form  of  cracking  by  carrying  out  the  distilla- 
tion of  crude  oil  without  the  assistance  of  steam  is  in 
everyday  use.  In  the  case  of  certain  crude  oils  an  increased 
yield  of  illuminating  oils  is  so  obtained.  In  distilling  for 
paraffin  wax,  a  less  viscous  distillate  is  obtained  by  distilling 


CRACKING  PROCESSES  233 

without  steam.  This  is  due  to  slight  cracking.  Even  in 
the  ordinary  processes  of  distilling  lubricating  oils  with 
steam  a  slight  yield  of  low-flash  distillate  is  obtained. 
When  distilling  certain  mixed  base  oils  down  to  coke  in  the 
usual  refinery  practice  considerable  cracking  takes  place. 
This  is  also  the  case  when  distilling  crude  oils  derived  from 
the  distillation  of  shale.  In  fact,  it  is  the  rule  that  a  certain 
amount  of  cracking  cannot  be  avoided,  however  carefully 
distillation  be  conducted. 

(b)  Distillation  in  the  Liquid  Phase  under  Pressure. 
— As  above  mentioned,  numerous  patents  have  been  taken 
out,  but  few  of  these  processes  have  found  any  technical 
application. 

The  Burton  process  is  very  extensively  used  in  the 
United  States,  gas  oil  being  the  basic  substance  usually 
treated.  This  gas  oil  is  distilled  in  a  cylindrical  still  under 
a  pressure  of  4  to  5  atmospheres  and  the  distillates  are 
condensed  under  the  pressure  generated  in  the  still  (U.S. 
Pat.  1049667,  January  7,  1913).  The  operation  is  carried 
out  in  a  still  of  the  ordinary  type,  specially  strengthened  to 
withstand  the  internal  pressure.  The  vapours  are  led  to 
an  ordinary  condenser  the  outlets  from  which  are  closed  by 
valves,  so  that  the  condensation  takes  place  under  pressure. 
The  product  obtained  has  a  decided  odour  and  is  of  a  light 
yellow  colour,  which  can  be  removed  by  refining.  It  is 
claimed  that  by  working  at  this  pressure  the  product  consists 
largely  of  paraffin  hydrocarbons.  If  the  condensation  is 
not  carried  out  under  pressure,  considerable  quantities  of 
olefines  are  found  in  the  distillate. 

Other  processes  have  been  designed,  operating  with 
tubular  stills  and  retorts.  These  have  the  advantage  that 
relatively  small  quantities  of  oil  are  in  the  plant  at  one  time. 
Fleming  uses  a  vertical  still,  claiming  that  coke  deposits 
much  less  readily  on  vertical  walls.  Many  devices  for 
protecting  the  bottoms  of  cracking  stills  have  been  devised, 
e.g.  that  of  Coast  (U.S.  Pat.  1345134  of  June  29,  1920)  in 
which  a  protective  layer  of  molten  alloy  kept  in  circulation 
is  used. 


234    PETROLEUM  AND  ALLIED  INDUSTRIES 

(c)  Cracking  in  the  Vapour  Phase. — When  working 
with  a  two-phase,  liquid,  and  vapour  system,  conditions  are 
limited  by  the  fact  that  for  any  particular  temperature  the 
corresponding  definite  vapour  pressure  must  be  employed. 
Therefore,  to  attain  the  high  temperatures  required,  corre- 
spondingly high  pressures  must  be  employed.  Moreover, 
temperature  and  pressure  cannot  be  varied  independently 
of  each  other.  With  a  single-phase  vapour  system  this 
objection  disappears. 

Several  processes  operating  on  the  principle  of  heating 
the  vapours  instead  of  the  oil,  have  met  with  some  measure 
of  commercial  success.  For  example,  Hall  (J S.C.I.,  1915, 
p.  1045)  designed  a  process  which  is  in  operation  at  present. 

The  oil  to  be  cracked,  a  heavy  kerosene  or  gas  oil,  is 
first  preheated  and  then  passed  through  a  cracking  coil, 
which  may  be  heated  up  to  600°  C.  This  coil  is  of  small 
diameter  (i  inch)  and  of  great  length  (over  300  feet).  The 
products  are  pumped  through  at  high  velocity,  little  or  no 
coke  being  deposited  in  the  tubes.  The  vapours  are  then 
allowed  to  expand  suddenly  into  a  vessel  of  large  diameter 
filled  with  packing  rings,  the  temperature  being  consequently 
reduced  to  about  325°  C.  Quantities  of  carbon  separate 
out  in  this  vessel.  The  vapours  are  then  passed  through  a 
dephlegmator  where  the  less  volatile  constituents  separate 
out,  the  rest  of  the  vapours  being  then  passed  through  a 
compressor  working  up  to  five  or  six  atmospheres.  The 
product  is  then  condensed  in  the  ordinary  way.  By  working 
at  higher  temperatures  aromatic  hydrocarbons  have  been 
produced  by  the  Hall  process,  the  loss  by  formation  of  non- 
condensable  gases  being  in  this  case,  however,  excessive. 

Another  example  of  a  process  of  this  type  is  that  of 
Rittman  (Bulletin  114,  U.S.  Bureau  of  Mines,  1916).  The 
Rittman  furnace  consists  of  a  battery  of  vertical  cracking 
tubes  of  diameter  up  to  10  inches  and  12  feet  in  length. 
The  vapours  of  the  gas  oil  to  be  cracked  are  heated  in 
these  tubes  at  pressures  up  to  6  or  7  atmospheres,  and 
temperatures  from  600°  to  700°  C.  according  to  circum- 
stances. These  tubes  are  provided  with  a  central  cleaning 


HYDROGEN ATING  PROCESSES  235 

rod  and  are  connected  at  their  lower  ends  to  a  tar  pot. 
An  attempt  was  made  to  utilize  this  process  for  the 
manufacture  of  benzene  and  toluene  during  the  war,  but 
no  measure  of  success  was  attained. 

In  other  forms  of  plant  for  cracking  in  the  vapour  phase 
superheated  steam  is  introduced.  For  example,  Greenstreet 
(Eng.  Pat.  16542,  July,  1912)  forces  a  mixture  of  oil  and 
steam  through  a  cracking  tube  ij  inches  diameter  and 
100  feet  in  length,  heated  to  a  cherry-red  heat,  under 
considerable  pressure.  Greenstreet  claims  that  in  this  way, 
mainly  paraffins  and  defines  are  produced. 

(d)  Hydrogenation   Methods. — The  classic  researches 
of  Sabatier  and  Senderens  on  the  catalytic  effect  of  nickel 
in  accelerating  hydrogenation  has  given  rise  to  the  modern 
industry    of    hardening    fats.     Numerous    attempts    have 
consequently  been  made  to  apply  this  process  to  the  hydro- 
genation of  petroleum  products.     Hydrogenation  by  means 
of  steam  has  also  been  tried  by  various  inventors,  so  far, 
however,  with  little  measure  of  success. 

Bergius  has  carried  out  pioneer  work  on  hydrogenation  at 
high  pressures.  He  claims  that  heavy  mineral  oils  may  be 
transformed  into  low  boiling  products  by  treatment  with 
hydrogen  at  400°  C.  under  a  pressure  of  100  atmospheres. 
Under  these  conditions  no  coke  is  formed,  and  the  amount  of 
uncondensable  gases  is  less  than  in  the  case  of  a  cracking 
process  (Zeit.  angew.  Chem.,  1921,  p.  341).  He  claims  that 
even  coal  can  be  so  treated  to  yield  large  percentages  of  oil. 
The  possibilities  of  such  a  process  are  very  fascinating  and 
foreshadow  the  eventual  manufacture  of  petroleum  products 
from  waste  vegetable  matter.  The  technical  difficulties, 
however,  of  working  at  such  high  pressures  are  very  great. 

Day  (U.S.  Pat.  826089,  July,  1906)  claims  to  hydrogenate 
unsaturated  hydrocarbons  by  bringing  them  into  contact 
with  hydrogen  and  a  catalyst  such  as  palladium  or  hydrogen 
at  high  pressure.  No  satisfactory  method  of  hydrogenation 
of  petroleum  hydrocarbons,  however,  has  so  far  been 
developed. 

(e)  Various  other  Methods. — The  well-known  use  of 


236    PETROLEUM  AND  ALLIED  INDUSTRIES 

aluminium  chloride  for  effecting  syntheses  in  organic 
chemical  research  work  has  suggested  its  application  in  this 
case  also,  Friedel  and  Craft  having  themselves  tried  the 
effect  of  this  reagent  on  petroleum  oils.  They  showed  that 
not  only  a  synthetic  action,  but  also  a  disruptive  action, 
may  be  effected.  Egloff  and  Moore  particularly  have  in- 
vestigated these  reactions  (Met.  and  Chem.  Eng.,  1916, 
p.  340).  McAfee  (Trans.  Am.  Inst.  of  Chem.  Eng.,  1915, 
p.  179)  has  studied  the  possible  application  of  the  method 
and  has  patented  a  process  (U.S.  Pat.  1235523,  July, 
1917)  for  which  he  claims  that  he  obtains  a  substantially 
complete  conversion  of  higher-temperature  boiling  petroleum 
oils  into  lower-temperature  boiling  oils.  He  operates  the 
process  by  passing  chlorine  into  the  oil,  containing  finely 
divided  aluminium  in  suspension.  The  chlorine  is  evolved 
mostly  in  the  form  of  hydrochloric  acid  gas  which  can  be 
recovered.  A  conversion  of  the  higher  boiling  oils  into 
benzine  is  claimed.  The  oil  during  the  process  must  be 
kept  in  agitation,  and  moisture  and  sulphur  compounds 
must  be  rigorously  excluded.  The  recovery  of  the  aluminium 
chloride  would  present  a  somewhat  difficult  problem. 

Attempts  have  also  been  made  to  bring  about  cracking 
by  submitting  oil  vapours  to  silent  electrical  discharges. 
Cherry,  Robertson,  and  others  have  suggested  such  methods. 

A  very  full  account  of  the  various  methods  which  have 
been  proposed  is  given  in  "  Gasoline  and  other  Motor  Fuels," 
by  Ellis  and  Meigs  (D.  van  Nostrand  Co.),  to  which  the 
reader  may  be  referred  for  further  information  on  this 
interesting,  but,  so  far,  incompletely  worked  out  subject. 


SECTION  G.— REFINERY  WASTE  PRODUCTS— 
THEIR  REGENERATION  AND  UTILIZA- 
TION 

IN  connection  with  various  refinery  processes,  particularly 
the  chemical  treating  and  filtration,  various  products 
result  which  are  too  often  allowed  to  run  to  waste.  Even 
in  the  case  of  crude  oil  itself  much  emulsion,  commonly 
called  B.S.,  accumulates  at  the  bottom  of  the  storage  tanks. 
This  material,  which  may  contain  large  percentages  of  oil, 
was  at  one  time  allowed  to  run  to  waste,  or  was  burnt.  It 
is  now  usually  treated,  either  by  the  electric  dehydration 
process,  or  by  means  of  the  super-centrifuge.  Both  these 
processes  have  been  described  in  Part  III.,  Section  D. 

From  the  distillation  of  crude  oil  and  more  particularly 
from  cracking  operations,  quantities  of  gas  or  light  vapours 
are  evolved.  These  consist  partly  of  condensable,  partly  of 
non-condensable  gases,  and  in  the  case  of  gases  from  cracking 
operations,  usually  contain  quantities  of  defines. 

The  condensable  gases  are  usually  absorbed  in  modern 
refineries  by  means  of  some  form  of  gas  absorber  or  scrubber, 
the  non-absorbable  gases  being  led  to  a  gasholder  and 
eventually  used  as  fuel.  In  certain  cases  the  gases  from 
cracking  stills  contain  propylene,  which  is  absorbed  in 
sulphuric  acid.  This,  on  subsequent  treatment  with  steam, 
liberates  propyl  alcohol,  which  is  utilized  in  admixture  with 
benzine  as  a  motor  spirit.  This  is  analogous  to  the  prepara- 
tion of  alcohol  from  the  ethylene  in  coal  gas  by  means  of  the 
Bury  process  (Chemical  Age,  August  28,  1920). 

Very  large  quantities  of  sulphuric  acid  sludge  result  from 
the  treatment  of  light  oils,  lubricants,  and  paraffin  wax. 
Much  attention  has  been  given  to  the  recovery  or  utilization 

237 


238    PETROLEUM  AND  ALLIED  INDUSTRIES 

of  these  acid  sludges,  in  many  cases,  however,  with  little 
success.  The  character  of  the  acid  sludge  depends  naturally 
on  the  character  of  the  oils  which  have  been  treated. 

In  many  cases  the  acid  sludge  is  merely  diluted  with 
water.  This  causes  a  quantity  of  oil  to  separate  out,  which 
is  skimmed  off  or  absorbed  in  a  heavy  oil  and  used  as  fuel. 
The  diluted  acid  cannot  usually  be  reconcentrated  success- 
fully as  it  still  contains  organic  matter  in  solution,  so  that  on 
concentration  reactions  take  place  resulting  in  the  evolution 
of  sulphur  dioxide  and  the  separation  out  of  carbonaceous 
matter  which  clogs  up  the  concentrating  plant.  In  many 
cases  it  pays  to  purchase  fresh  acid  rather  than  concentrate 
the  waste. 

In  the  case  of  acid  sludges  which  result  from  the  treat- 
ment of  lubricating  oils,  they  may  be  treated  with  live  steam, 
the  oils  which  separate  out  being  mixed  with  petroleum 
residues  and  used  as  fuel.  If  the  material  separating  out 
from  the  sludge  is  of  an  asphaltic  nature  it  may  be  incorpor- 
ated with  lime  and  used  as  an  asphaltic  waterproof  material 
(Baskerville,  J.S.C.L,  March  15,  1920)  (vide  also  "  Sludge 
asphalts,"  p.  228). 

The  diluted  acid  is  in  some  cases  neutralized  with  lime 
and  the  precipitated  calcium  sulphate  removed.  The 
solution  then  contains  calcium  snlphonates  which  may  be 
salted  out  by  calcium  chloride.  These  calcium  sulphonates 
37ield  sulphonic  acids  from  which  soaps  may  be  prepared. 
As  the  calcium  and  magnesium  sulphonates  are  soluble  in 
water,  soaps  made  from  these  sulphonic  acids  will  produce 
good  lathers  with  sea  water  (Divine,  U.S.  Pat.  1330624). 

The  sludge  obtained  from  the  treatment  of  lubricating 
oils  ma}7,  after  dilution  and  removal  of  the  diluted  acid,  be 
incorporated  with  liquid  fuel  or  thin  asphalt  to  make  a 
hot-neck  grease.  The  diluted  acid,  freed  from  oily  matters, 
may  be  concentrated  down  and  then  allowed  to  flow  into  a 
retort  kept  full  of  concentrated  acid  through  which  a  current 
of  air  is  blown.  The  organic  matter  is  thus  destroyed  and 
the  acid  vapours  given  off  may  be  condensed  and  concen- 
trated (Ger.  Pat.  221615,  June  19,  1909).  Much  work 


REFINERY   WASTE  PRODUCTS  239 

still  remains  to  be  done  before  the  problem  of  the  recovery 
of  the  waste  sulphuric  acid  can  be  really  satisfactorily  solved. 

Quantities  of  waste  soda  sludge  from  the  treating  of 
petroleum  distillates  also  result.  These  sludges  contain, 
in  addition  to  much  free  soda,  sodium  naphthenates.  These 
may  be  obtained  by  concentrating  down  the  lye  and  salting 
out  with  common  salt.  The  naphthenates  (soaps)  separate 
out  and  may  be  freed  from  excess  of  water.  These  soaps 
can  be  used  as  low-grade  soaps,  but  they  have  an  objectionable 
odour.  The  naphthenic  acids  themselves  may  be  liberated 
by  the  addition  of  sulphuric  acid.  They  may  be  used  as 
antiseptics,  timber  preservatives,  solvents  for  varnish, 
resins,  and  as  substitutes  for  turkey  red  oil. 

Markownikoff  has  shown  that  these  naphthenic  acids 
belong  to  a  group  with  the  general  formula  CnH2n-2^2» 
being  carboxylic  acids  of  the  hydrocarbons  of  the  naphthene 
series.  Several  of  the  lower  members  of  the  series,  e.g. 
C6HnCOOH,  sp.  gr.  0-950,  b.  pt.  216  °C.,  have  been  isolated. 
(N.  Chercheffsky,  "  I<es  Acides  due  Naphte."  Paris,  Dunod 
et  Pinat.) 

From  the  filtration  and  treatment  of  lubricating  oils, 
kerosenes  and  paraffin  wax  by  means  of  fuller's-earths,  much 
impregnated  powder  is  obtained. 

In  the  case  of  powders  from  the  treatment  of  kerosene, 
the  material  is  first  treated  with  water.  This  causes  the 
bulk  of  the  absorbed  oil  to  separate  out.  The  oil  is  used  as 
fuel.  The  sludge  powder  is  then  dried  and  regenerated  by 
being  passed  through  one  of  the  ordinary  type  of  roasting 
furnaces. 

The  black  powder  obtained  by  the  filtration  of  lubricating 
oils  is  usually  first  treated  with  benzine.  The  benzine 
solution  is  then  concentrated  down,  the  residue  furnishing  a 
low-grade  lubricant,  the  benzine  being  distilled  off,  condensed 
and  re-used.  The  resulting  powder  is  then  roasted. 

The  powders  left  after  the  treatment  of  wax  are 
either  extracted  by  benzine,  or  steamed  out,  the  latter  being 
the  cheaper  process.  The  wax-free  powder  may  be  again 
regenerated  by  roasting. 


240    PETROLEUM  AND  ALLIED  INDUSTRIES 

The  lead  sulphide  sludge  obtained  as  a  by-product  from 
the  treatment  of  oils  by  means  of  the  sodium  plumbite 
process  is  usually  returned  to  the  lead  smelters. 

Automobile  lubricating  oils  after  use  may  be  easily 
cleaned  and  reconditioned  by  filtration  and  washing  with 
sodium  carbonate  solution,  any  dissolved  benzine  being 
removed  by  evaporation.  Such  reconditioned  oils  may  be 
re-used  with  complete  satisfaction  (W.  F.  Parish,  paper  read 
before  Am.  Chem.  Soc.,  Rochester,  1921). 


PAKT  VIII.— THE  CHARACTERS  AND 
APPLICATIONS  OF  PETROLEUM 
PRODUCTS 

[The  characters  and  applications  of  the  naturally  occurring  gases,  solid 
bitumens  and  pyrobitumens,  and  the  mineral  waxes  have  already 
been  dealt  with,  vide  Parts  II.,  V.  and  VI.  The  characters  and  applica- 
tions of  the  manufactured  products  will  be  dealt  with  in  this  part.] 

SECTION  A.— BENZINES 

THE  volatile  liquid  products  are  utilized  chiefly  as  motor 
fuels  and  as  solvents.  Relatively  small  quantities  find  special 
applications,  e.g.  the  most  volatile  fractions  may  be  used 
as  refrigerants.  Wght  benzines  boiling  completely  below 
100°  C.  are  used  for  carburetting  air  to  make  the  so-called 
air  gas  or  petrol  gas,  often  used  for  lighting  country  houses 
far  removed  from  coal-gas  works. 

Quantities  of  special  boiling-point  benzines  are  used 
for  the  extraction  of  oils  from  seeds.  The  range  of  boiling 
point  required  varies  according  to  the  type  of  extraction 
plant  in  use.  Benzines  of  boiling  point  ranges  80°  to 
100°  C.,  90°  to  110°  C.,  and  100°  to  120°  C.  are  in  common 
use.  Such  benzines  should  be  well  fractionated  and  well 
refined  to  get  rid  of  any  constituents  of  strong  odour.  A 
special  range  of  boiling  point  is  demanded  for  such  benzines 
in  order  to  exclude  both  the  light  volatile  fractions,  which 
would  bring  about  high  working  losses,  and  the  higher 
boiling-point  constituents  which  would  not  be  readily 
evaporated  from  off  the  extracted  oil  solution  (Shrader, 
"  Solvent  Extraction  in  the  Vegetable  Oil  Industry,"  Chem. 
and  Met.  Eng.t  vol.  25,  p.  94). 

Quantities  of  benzine,  sometimes  of  special  boiling-point 
p.  241  !6 


242     PETROLEUM  AND   ALLIED  INDUSTRIES 

range,  are  used  as  solvents  for  rubber  in  the  manufacture  of 
fine  rubber  goods. 

Very  large  quantities  of  heavy  benzine,  or  rather  light 
kerosene,  are  used  under  the  names  of  "  white  spirit  "  or 
"  mineral  turps  "  in  the  manufacture  of  paints,  varnishes, 
and  so  forth.  In  order  to  comply  with  regulations  such 
white  spirits  are  distilled  to  have  flash-points  over  73°  F. 
The  final  boiling  point  varies  according  to  requirements, 
grades  boiling  between  140°  C.  and  200°  C.,  and  others  with 
final  boiling  points  up  to  250°  C.,  are  on  the  market. 

The  bulk  of  the  light  petroleum  distillates  under  the 
names  of  motor  spirits,  petrols,  benzines,  naphthas,  and  gaso- 
lines are  consumed  as  motor  fuels. 

The  subject  of  the  efficiency  of  a  motor  fuel,  and  the 
factors  on  which  this  depends,  is  one  which  has  received 
much  attention  during  the  last  two  or  three  years.  It  is  a 
subject  of  great  importance,  as  the  urgent  necessity  for 
economy  in  fuel  consumption  is  being  brought  to  the  fore 
owing  to  the  rapid  increase  in  the  output  of  motor  vehicles, 
the  rate  of  increase  of  which  at  the  present  time  tends  to 
exceed  that  of  increase  of  the  petrol  supplies.  This  demand 
for  motor  spirits  has  of  late  years  increased  so  enormously 
that  at  least  90  per  cent,  of  the  production  of  light 
petroleum  fractions  is  used  for  this  purpose.  The  following 
figures  illustrate  this  : — 


1 

. 

Year. 

Total  consumption  in  U.S.  of  motor 
spirit  in  automobiles  in  millions  of 
U.S.  gallons  (approx.). 

spirit  in  U.S.  in  millions 
of  U.S.  gallons 
(approx.). 

igll 

250  i 

e.  31*2  per  cent,  of 

800 

1913 

450 

.   37'5 

Jt 

I2OO 

1915 

850 

,   48-5 

tl 

1750 

1917 

1750 

,    62-5 

t> 

2800 

1919 

3400 

.    85 

lt 

4000 

I92O 

3900 

,    82 

„ 

4750 

In  consequence  of  this  ever-increasing  demand  strenuous 
efforts  have  been  made  to  increase  the  production  of  motor 
spirit  in  every  way  possible.  This  has  been  effected  in  the 
main  in  three  ways  :  (i)  by  increasing  the  yield  obtained  from 


BENZINES 


243 


the  crude,  (a)  by  improvement  in  refinery  methods,  (b)  by 
alteration  of  quality ;  (2)  by  increasing  production  of 
gasoline  extracted  from  natural  gases ;  and  (3)  by  the  pro- 
duction of  gasoline  made  by  cracking  processes. 

The  changes  in"  quality  of  the  gasoline  produced  in  the 
United  States  is  indicated  by  the  increase  in  the  final  boiling 
point,  which  has  taken  place  in  spite  of  improved  methods  of 
refining. 


Year. 

Percentage  distilling  to  100°  C. 

Final  boiling  point  °C. 

1915 

40 

185 

1917 

30 

2OO 

1919 

25 

220 

1920 

22 

230 

The  following  table  gives  the  production  of  gasoline  in 
the  United  vStates  from  natural  and  casing-head  gas  (Dykema, 
U.S.  Bureau  of  Mines,  Bulletin  76)  : — 


Year. 

Gasoline  produced. 
U.S.  gallons. 

Average  yield  per 
1000  cu.  ft.  of  gas. 

No.  of  plants. 

I9II 

7,425,800 

3-00 

I76 

1912 

I2,o8l,200 

2  '60 

250 

1913 

24,060,800 

2'43 

341 

1914 

42,652,600 

2'43 

386 

1915 

65,364,7°° 

2'57 

414 

1916 

103,492,700 

0-496 

596 

1917 

217,884,100 

0-508                           886 

In  1914  the  production  of  gasoline  by  cracking  amounted 
to  little  more  than  i  per  cent,  of  the  total  output ;  in  1920 
this  figure  had  increased  to  nearly  5  and  is  steadily  increasing. 

The  characters  of  a  motor  spirit  depend  on  both  its 
physical  properties  and  chemical  composition.  In  countries 
where  benzine  is  sold  by  volume,  the  specific  gravity  is 
naturally  a  factor  of  some  importance,  as  it  determines  the 
weight  of  fuel  per  gallon  or  litre. 

The  point  of  prime  importance  to  the  user  is  the  obtain- 
ing of  the  maximum  work  for  the  money  expended.  The 
calorific  value  of  the  motor  fuel  per  unit  volume  is  thus  of 


244    PETROLEUM  AND  ALLIED  INDUSTRIES 

great  importance  in  countries  where  motor  fuels  are  sold  by 
volume. 

The  calorific  value  per  unit  weight  of  the  paraffins  is 
higher  than  that  of  the  naphthenes,  which  is  in  turn  higher 
than  that  of  the  aromatic  hydrocarbons.  The  specific 
gravities  of  these  three  classes  of  hydrocarbons  (in  the  case 
of  the  members  in  most  general  use  as  motor  spirits)  vary 
in  the  other  direction.  As  a  result  of  this  the  calorific  value 
per  unit  volume  is  largest  in  the  case  of  the  aromatic  hydro- 
carbons. 


Hydrocarbon. 

Sp.  gr. 

B.Th.U.'s 
perlb. 

B.Th.U.'s  per 
gallon. 

Heptane  (paraffin) 
Hexahydrobenzene  (naphthene) 
Toluene  (aromatic) 

0-688 
0776 
0-884 

19,400 
18,900 
17,660 

133.470 
140,660 
153,640 

If,  therefore,  the  high  specific  gravity  of  any  motor  fuel 
is  caused  by  the  presence  of  naphthenes  and  aromatics 
and  not  of  paraffins  of  high  boiling  point,  the  high  specific 
gravity  is  a  decided  advantage. 

Specific  gravity  alone  is  utterly  useless  as  a  criterion  of 
quality  for  obvious  reasons.  A  mixture  of  light  benzine 
and  kerosene,  quite  unsuitable  as  a  motor  fuel,  may  have  the 
same  specific  gravity  as  a  good  homogeneous  benzine  of 
reasonable  boiling  range.  A  sample  of  motor  benzol,  an 
excellent  fuel,  may  have  a  specific  gravity  higher  than  that 
of  a  light  paraffin  gas  oil.  Unfortunately,  owing  to  the  fact 
that  the  motor  fuels  first  on  the  English  market  were  of 
the  paraffin  type,  the  idea  that  low  specific  gravity  was  a 
criterion  of  quality  became  deeply  rooted  in  the  minds  of 
the  motoring  public,  a  mistaken  idea  which  dies  very  hard. 

The  range  of  boiling  point  is  a  character  of  more  import- 
ance. The  fuel  must  contain  sufficient  light  fractions  to 
render  it  sufficiently  volatile  to  enable  starting  up  the 
engine  at  ordinary  winter  temperatures  without  unreasonable 
difficulty.  The  degree  of  ease  with  which  any  engine  can 
be  started  depends  as  much  or  more  on  the  engine  as  on  the 


BENZINES 


245 


fuel,  the  design  of  the  induction  system  having  very  much 
influence.  However,  for  a  definite  engine,  the  ease  with 
which  a  fuel  will  start  up  depends  on  two  factors,  (a)  the 
range  of  air  mixtures  over  which  the  fuel  will  burn,  and 
(b)  its  volatility.  As  regards  the  burning  range,  all  petroleum 
motor  spirits  are  similar.  Only  mixtures  of  air  and  benzine 
vapour,  containing  between  2  and  5  per  cent,  approximately 
of  the  latter,  are  explosive.  Alcohol,  on  the  contrary,  has  a 
much  larger  range,  viz.  from  4  to  14  per  cent. 

The  volatility  of  a  fuel  depends  on  its  composition, 
not  only  on  the  percentage  of  any  particular  volatile  hydro- 
carbon, but  on  the  relative  quantities  of  the  less  volatile 
fractions  too.  In  a  rough  way,  volatility  may  be  taken  as 
measured  by  vapour  pressure,  but  as  the  conditions  under 
which  evaporation  take  place  in  a  vapour  pressure  apparatus 
and  in  an  internal  combustion  engine  (the  relative  proportions 
of  vapour  and  liquid  being  so  different)  differ  so  greatly, 
conclusions  drawn  from  vapour  pressure  determinations 
may  be  quite  erroneous.  The  following  table  gives  the 

vapour  pressure  of  various  fuels  at  o°  C.  : — 

Vapour  pressure 
Fuel.  in  mm.  at  o°  C. 

w-pentane  . .  . .         . .         . .  183 

tt-hexane  . .  . .         . .         . .  45 

w-heptane  ..                                ..  n*5 

Benzene  . .  . .         ....  26 

Toluene  ..  ,.         ..          ..  9 

Cyclohexane  ..  27*5 

Ethyl  alcohol  . .  12 

The  following  table  gives  the  boiling-point  ranges  of 
a  number  of  motor  spirits  and  their  vapour  pressures  : — 


Fuel. 

Sp.  gr. 
15°  C. 

Distillation  test,  boiling  up  to 

Final 
boiling 
point. 

Vapour  pres- 
sure at  o°  C. 

80°  C. 

100°  C. 

120°  C.j  140°  C. 

160°  C. 

I 

0782 

2 

18 

55 

83 

96 

165 

28  mm. 

2 

0725 

12 

55 

82 

93 

98 

1  60 

55     .. 

3 

0704 

27 

67 

86 

95 

— 

152 

70     ., 

4 

0760 

15 

66 

89 

97 

165 

19     „ 

246    PETROLEUM  AND  ALLIED  INDUSTRIES 

Ricardo,  in  a  series  of  articles  in  the  Automobile 
Engineer,  February  to  August,  1921,  has  dealt  with  this 
subject  among  others.  He  finds  that  the  rise  of  temperature 
brought  about  in  the  induction  pipe  of  a  standard  engine, 
run  under  standard  conditions  with  heat  supplied  to  the 
air  induction  pipe  at  a  standard  rate,  gives  a  measure  of 
the  volatility  of  a  motor  fuel.  This  figure  involves  latent 
heat  as  well  as  vapour  pressure. 

The  upper  end  of  the  range  of  boiling  point  is  in  some 
respects  of  great  importance.  If  the  motor  fuel  contain 
fractions  of  too  high  boiling  point,  then  a  certain  amount 
of  condensation  will  take  place  on  the  cylinder  walls,  and 
the  high  boiling  fractions  so  condensed  will  gradually  find 
their  way  past  the  pistons  into  the  crank-case,  where  they 
will  dilute  the  engine  oil.  This  will  sooner  or  later  give 
rise  to  bearing  trouble.  With  a  motor  spirit  of  too  high 
final  boiling  point  it  will  be  found  necessary  to  change  the 
lubricating  oil  more  frequently.  A  final  boiling  point  of 
220°  C.  may  be  taken  as  permissible,  although  many  motor 
spirits  on  the  market,  particularly  in  the  United  States, 
have  final  boiling  points  exceeding  this.  The  high  final  boiling 
point  is  the  chief  objection  to  benzol-kerosene  mixtures  as 
motor  fuels. 

Of  very  much  greater  importance,  however,  is  the 
question  of  the  efficient  burning  of  the  fuel  in  the  motor,  as 
on  the  efficiency  depends  the  fuel  consumption  per  brake 
horse-power  hour,  a  question  of  the  greatest  importance  to 
the  user  and  to  the  world  at  large.  It  is  in  this  connection 
that  the  chemical  composition  of  the  fuel  plays  such  a  very 
important  part. 

The  efficiency  of  an  internal  combustion  motor,  assuming 
that  the  working  fluid  is  a  perfect  gas,  is  given  by  the  formula 

•y-l 


y  being  the  ratio  of  the  specific  heats  of  a  gas. 
r  being  the  compression  ratio,  i.e.  the  ratio  of  the  volume 
of  the  cylinder  at  the  bottom  of  the  stroke  to  that  at  the 


BENZINES  247 

top.  As,  however,  a  mixture  of  benzine  vapour  and  air  is 
not  a  perfect  gas,  this  expression  must  be  modified.  Tizard 
and  Pye  (Automobile  Engineer,  February,  1921)  have 

/j\°  '258 
found  that  the  expression  E  =  i  —  ( -  J        gives  the  correct 

values. 

It  can  be  seen  from  this  formula  that  the  efficiency 
of  an  internal  combustion  engine  varies  with  the  com- 
pression ratio — 

Compression 

ratio.  Air  cycle  efficiency. 

4:1        . .         . .          . .         42*56  per  cent. 

5:i       ••         ...         ..         47*47       » 
6:1        51-16       „ 

7:1       ••         ••         ••        53*98       „ 

Experiments  carried  out  in  a  special  variable  compression 
engine  by  Ricardo,  gave  the  following  actual  figures  for 
indicated  thermal  efficiency  : — 

Compression  Actual  indicated  Efficiency  relative  to 

ratio.  thermal  efficiency.  air  cycle  efficiency. 

4:1        . .       277  per  cent.  . .         65-0  per  cent. 

5:1        ..31-9        „  ..         67-1 

6 :  i        . .       35'3        N  •  •  •  68-8       „ 

7^  -••       37'5        »  ••         69-6       „ 

The  advantage  of  using  an  engine  of  high  compression  ratio 
is  thus  obvious. 

The  influence  of  the  chemical  composition  of  the  motor 
fuel  here  comes  particularly  into  play. 

The  maximum  compression  ratio  and  therefore  maximum 
efficiency  at  which  a  particular  internal  combustion  engine 
can  be  run  is  limited  in  practice  by  the  fact  that  when  this 
reaches  a  certain  value  dependent  on  the  particular  fuel, 
detonation  (the  knocking  or  pinking  of  the  motorist)  sets  in, 
and  this,  if  allowed  to  continue,  soon  brings  about  preignition 
with  consequent  loss  of  power.  When  detonation  occurs 
in  practice,  the  throttle  must  be  partially  closed,  which  is 
tantamount  to  lowering  the  compression  ratio  of  the  engine, 


248    PETROLEUM  AND  ALLIED  INDUSTRIES 


or  the  spark  must  be  retarded,  either  of  which  means  loss 
of  efficiency. 

This  subject  has  been  investigated  fully  by  Ricardo 
(loc.  cit.),  who  examined  the  behaviour  of  various  fuels  and 
as  far  as  possible  pure  hydrocarbons  in  a  special  engine,  the 
compression  ratio  of  which  could  be  varied  and  set  to  any 
particular  value  even  during  the  running  of  the  engine. 
These  investigations  proved  very  decisively  one  point, 
namely,  that  of  the  three  types  of  hydrocarbons  found  in 
petroleum  motor  fuels,  the  aromatic  hydrocarbons  showed 
least  tendency  to  detonate,  the  paraffins  most,  the 
naphthenes  occupying  an  intermediate  position.  The 
following  table  gives  a  list  of  some  fuels  examined  and  the 
maximum  compression  ratio  at  which  they  could  be  used 
without  excessive  detonation  in  the  experimental  engine  :  — 


Fuel. 

Toluene 

Ethyl  alcohol    . . 

w-xylene 

Benzene 

Cyclohexane 

Cycloheptane    . . 

w-Hexane 

w-Heptane 

Ether 


Highest  usable 
compression. 


7 '50 
7-40 
6*90 

5  '9° 
5*90 
5-25 
375 
2*95 


The  next  table  gives  the  chemical  composition  of  certain 
typical  fuels  examined  by  Ricardo,  together  with  the 
maximum  compression  ratios  at  which  they  could  be  used 
in  that  engine  : — 


Composition  by  weight. 

Fuel. 

Sp.gr.  is°C. 

Paraffin,  per    I     Aromatics, 

Naphthenes,     ;  compressioi 

cent. 

per  cent. 

per  cent. 

I 

0782 

26 

39 

35 

6-0 

2 

0767 

IO'2 

4-8 

85 

5  '9 

3 

0760 

38 

15 

47 

5'35 

4 

0727 

61 

8'5 

3°'5 

5'25 

5 

0704 

80-5 

4  '3 

15-2 

5-05 

6 

0718 

63-3 

17 

35'° 

4-85 

BENZINES 


249 


Ricardo  has  also  shown  that  the  heats  of  combustion 
per  unit  volume  of  the  air-fuel  mixtures  (in  the  correct 
proportions  for  complete  combustion)  show  little  variation 
for  all  volatile  hydrocarbon  fuels. 


Fuel. 

Calorific  value, 
B.Th.U.'s  per  Ib. 

Relative  beats  of  combus- 
tion per  unit  vol.  of  air- 
fuel  mixture  giving 
complete  combustion. 

Hexane 
Heptane 
Benzene     -  • 
Toluene 
Cyclohexane 
Kerosene 

19,390 
19,420 
17,460 
17,660 
18,940 
19,100 

46-0 
46-06 
46-9 
46-9 
46-08 
46-14 

The  practical  result  of  this  is  that  in  an  engine  of  such 
low-compression  ratio  (and  therefore  low  efficiency)  that  any 
hydrocarbon  fuel  could  be  used  therein  without  detonation, 
the  relative  efficiencies  of  all  such  fuels  would  be  about  the 


same. 


This  is  borne  out  by  the  following  results  : — 


Fuel. 


Sp.gr.  15°  C. 


Minimum  consumption  per  I.H.P. 
hour. 


Lbs. 


Pints. 


I 

0782 

0-432 

0-442 

2 

0767 

0-425 

°'443 

3 

0-760 

0*422 

°'445 

4 

0-727 

0-421 

0-463 

5 

0-704 

0-414 

0-471 

6 

0-718 

0-415 

0-462 

If,  however,  the  minimum  consumptions  per  I.H.P.  hour 
are  compared  at  the  maximum  compression  ratios  at  which 
the  fuels  can  be  used,  then  the  effect  of  the  increase  of 
efficiency  so  obtained  is  most  marked. 


Fuel. 

Sp.  gr.  15°  C. 

Highest  usable 
compression. 

Minimum  compression  per  I.H.P. 
hour. 

Lbs. 

Pints. 

I 

2 

3 
4 

6 

0782 
0767 
0-760 
0727 
0-704 
0718 

6-0 

5  '9 
5  '35 
5*25 
5'°5 
4-85 

G'393 
0-389 
0-407 
0-410 
0-412 
0-422 

0-402 
0-405 
0-428 

0-451 
0-469 
0-471 

250    PETROLEUM  AND  ALLIED  INDUSTRIES 

The  practical  value  of  these  Jesuits  lies  in  the  fact  that  a 
motor  spirit,  rich  in  paraffins  and  poor  in  aromatics  and 
naphthenes,  will  detonate  in  the  average  engine  when  the 
spark  is  fully  advanced  and  the  throttle  open.  It  is,  there- 
fore, advantageous  even  in  engines  of  low-compression 
ratio  to  use  motor  spirits  rich  in  aromatics  and  naphthenes 
if  obtainable.  In  the  case  of  aeroplane  engines,  where 
efficiency  is  of  such  great  importance,  which  are  usually 
therefore  of  high-compression  ratio,  only  motor  fuels  of  low 
paraffin  content  can  be  used. 

The  motor  spirits  marketed  in  different  localities  show 
much  variation  in  quality,  this  being  largely  due  in  the 
first  place  to  the  character  of  the  crude  oils  from  which  they 
are  manufactured.  The  specific  gravity  may  vary  much, 
according  to  chemical  composition  and  boiling-point  range. 
Spirits  composed  mainly  of  volatile  paraffin  hydrocarbons 
may  have  specific  gravity  as  low  as  0*680.  Spirits  relatively 
rich  in  aromatic  and  naphthene  hydrocarbons  may  have 
specific  gravity  0*760  or  more  (pure  benzene  sp.  gr.  0*884). 
The  initial  boiling  point  (the  determination  being  carried 
out  in  an  Engler  flask  of  standard  dimensions,  under  standard 
conditions)  may  be  as  low  as  30°  C.  or  as  high  as  60°  C.  The 
percentage  boiling  below  100°  C.  usually  varies  between 
10  and  70  per  cent.  The  final  boiling  point  lies  usually 
between  160°  C.  and  200°  C.,  but  is  occasionally  as  low  as 
130°  C.  and  often  as  high  as  230°  or  240°  C.  As  the  method 
of  testing  of  motor  spirits  is  so  well  described  in  various 
works,  this  subject  will  not  be  dealt  with  here,  but  a 
few  words  on  the  interpretation  of  the  results  will  not 
be  out  of  place.  The  specific  gravity  must  be  interpreted 
in  connection  with  the  boiling-point  range  and  chemical 
composition.  A  high  specific  gravity  with  components  of 
normal  boiling-point  range  would  indicate  presence  of 
naphthenes  and  aromatics.  The  boiling  point  or  distillation 
test  would  show  up  the  presence  of  excessive  quantities 
of  the  very  volatile  casing-head  gasolines  or  the  presence 
of  constituents  of  too  high  boiling  point. 

Tests  are  usually  carried  out  to  show  that  the  spirit  has 


BENZINES  251 

been  adequately  refined  and  is  free  from  appreciable  con- 
tamination with  organic  sulphur  compounds  which  impart 
to  it  an  objectionable  odour.  As  the  majority  of  the  tests 
are  of  an  empirical  nature,  there  is  great  diversity  of  method, 
but  steps  are  being  taken  to  unify  and  standardize  methods. 


GENERAL   REFERENCES   TO   PART   VIII.,  SECTION   A. 

Dean,  "  Motor  Fuels,"  Jour.  Franklin  Inst.,  1920,  p.  269. 

Ellis  and  Meigs,  "  Gasoline  and  other  Motor  Fuels."  D.  Van  Nostrand 
Co.,  New  York. 

Formanek,  "  Benzine  and  Mineral  Lubricants."  Scott,  Greenwood 
and  Son. 

Pogue,  "  Economics  of  Petroleum,"  chapter  ix.  J.  Wiley  and  Sons, 
New  York. 


SECTION  B.— KEROSENES,   ILLUMINATING 
OILS,   ETC. 

THE  distillates  which  come  off  after  the  benzine  fractions 
and  before  the  gas-oil  fractions,  are  worked  up  into  kerosenes. 
There  is  no  hard-and-fast  line  of  demarcation  between 
benzine  on  the  one  hand  and  gas  oil  on  the  other.  At 
one  time,  when  benzine  was  practically  a  by-product  of  no 
value,  as  much  as  possible  of  the  low  boiling  constituents 
was  included  in  the  kerosene,  with  the  result  that  this 
product  had  almost  invariably  a  low  flash-point  as  near  the 
legal  limit  (73°  or  76°  F.)  as  might  be.  Nowadays,  however, 
as  improved  motor  engines  can  deal  with  less  volatile 
benzines  the  tendency  is  to  include  part  of  the  lower  boiling 
constituents  of  what  was  formerly  made  into  kerosene,  in 
the  benzine  fraction.  The  removal  of  these  lighter  fractions 
from  the  kerosene,  has  brought  about  the  necessity  for  the 
removal  of  a  balancing  quantity  of  heavier  fractions  of  higher 
boiling  point  (which  now  go  into  gas  oil).  Kerosenes  now- 
adays have  thus  a  higher  flash-point  and  a  narrower  boiling- 
point  range  than  was  formerly  the  case,  so  that  an  improve- 
ment in  the  quality  of  the  kerosene  generally  marketed  has 
thus  been  effected. 

Kerosene  was  at  one  time  the  mainstay  of  the  petroleum 
industry.  As  a  cheap  illuminant  it  has  been  aptly  termed 
"  one  of  the  greatest  of  all  modern  agents  of  civiliza- 
tion." The  recent  great  developments  in  automobile 
engineering  and  the  increased  use  of  liquid  fuels,  and  to  a 
less  extent  asphalts,  have  forced  kerosene  to  take  a  back 
seat. 

252 


KEROSENES,   ILLUMINATING  OILS,   ETC.     253 
This  is  well  illustrated  by  the  following  table  :— 

Kerosene  production 
expressed  as  percentage 
Year.  of  crude  oil  treated. 

1899 58 

1904 48 

1909  ..  -.33 

1914  ..  ..  24 

1916 14 

1918  ....  ..  13-3 

1920 I2'7 

(Pogue,  "  Economics  of  Petroleum  "). 

The  above  figures  refer  to  the  United  States  only,  but 
may  be  taken  as  indicating  the  position  generally.  In 
1899  kerosene  represented  60  per  cent,  of  the  value  of  the 
total  petroleum  products  ;  in  1920  only  14  per  cent. 

Kerosenes  show  great  variation  in  quality  according 
to  (a)  the  nature  of  the  crude  oil,  (b)  the  method  of  distilla- 
tion, and  (c)  the  method  of  refining. 

The  quality  of  the  kerosene  from  the  point  of  view  of 
an  illuminant  can  only  be  spoken  of  relatively  to  the  type 
of  lamp  used.  With  the  ordinary  type  of  lamp,  kerosenes 
composed  largely  of  paraffin  hydrocarbons  (other  things 
being  equal)  give  the  highest  candle  power ;  those  composed 
mainly  of  naphthenes  do  not  burn  so  well  and  those  rich  in 
aromatics  will  burn  only  with  a  smoky  flame.  With  certain 
suitable  lamps,  however,  kerosenes  rich  in  aromatics  will 
give  higher  candle  power  than  those  rich  in  paraffins.  For 
vaporizing  lamps,  on  the  other  hand,  all  types  behave  well. 

The  method  of  distillation,  or  rather  the  cutting  of  the 
distillates,  may  be  effected  so  as  to  produce  various  grades. 
For  example,  in  the  United  States,  it  is  usual  to  manufacture 
two  grades,  one  by  taking  a  cut  from  the  middle  fractions  of 
the  distillate,  and  one  by  mixing  the  lighter  and  the  heavier 
cuts  together.  The  former  naturally  gives  a  finer  and 
more  homogeneous  product,  although  the  specific  gravity 
of  the  latter  may  be  the  same. 

The  method  of  refining  is  important,  as  products  of  fine 


254    PETROLEUM  AND  ALLIED  INDUSTRIES 

colour  (the  so-called  water  white)  are  in  demand.  For 
kerosenes  used  for  signal  lamps  and  so  forth,  which  demand 
efficient  burning  over  long  periods,  carefully  refined  products 
are  necessary ;  for  native  lamps  of  simple  construction,  on 
the  other  hand,  poorly  refined  grades  serve  quite  well. 
The  majority  of  kerosenes  now  in  the  market  have  specific 
gravities  varying  from  0780  to  0-825  or  more.  Flash-points 
are  nowadays  about  40°  C.  (Abel  Pensky  test),  but  may  be  as 
high  as  65°  C.  The  low  limit  for  flash-point  for  various 
countries  varies  much,  ranging  from  24°  C.  to  45°  C.  or  more. 
The  boiling-point  range  usually  extends  from  150°  C.  to 
300°  C.,  as  determined  by  standard  Engler  flask.  The 
colour  varies  from  a  distinctly  yellow  tint  to  nearly 
colourless. 

The  following  table  gives  analyses  of  a  few  types  of 
kerosenes  marketed,  from  which  the  considerable  variation 
in  properties  may  be  noticed  : — 


Percentage  boiling  in  Engler  flask  (vol.)  up  to  °C. 

Kerosene. 

Sp.  gr. 
15°  C. 

Flash- 
point °C. 

j                     | 

175 

200 

250 

275 

300 

A 

0783 

39 

23 

65 

97 

100 

B 

0-804 

43 

7 

34 

75 

90 

96 

C 

0-807 

53 

15 

66 

85 

92 

D 

0-814 

48 

— 

16 

67 

85 

89 

E 

0-815 

69 

— 

3 

60 

85 

96 

F 

0-818 

31 

3° 

55 

85 

93 

98 

G 

0-820 

36 

15 

32 

68 

82 

91 

H 

0-828 

36 

18 

52 

93 

98 

Kerosene. 

lamp  to  90  per  cent,  consumed. 

hour  in  grams. 

A 

36 

1-86 

B 

30 

i'95 

C 

16 

3-87 

D 

20 

3-64 

E 

27 

2  '2O 

F 

18 

3  '3 

H 

21 

3  '9 

KEROSENES,   ILLUMINATING  OILS,  ETC.    255 

The  qualities  of  a  kerosene  must  be  considered  in  relation 
to  the  purpose  for  which  it  is  to  be  used.  Kerosenes  are 
used  chiefly  for  illuminating  purposes  in  wick-fed  lamps, 
but  are  also  largely  used  as  motor  fuels  for  types  of  internal 
combustion  engines  fitted  with  vaporizing  devices,  and  for 
semi-diesel  motors,  and  to  a  much  less  extent  for  other 
purposes  of  minor  importance  such  as  insecticides  and 
flotation  oils. 

For  illuminating  purposes  the  kerosene  should  have 
a  normal  range  of  boiling  points.  The  final  boiling  point 
should  not  much  exceed  300°  C.,  as  the  higher  boiling-point 
constituents  are  lacking  in  capillary  power  and  do  not  flow 
well  up  the  wick,  especially  as  the  level  of  the  kerosene 
in  the  container  falls.  Constituents  of  too  high  boiling  point 
also  tend  to  bring  about  charring  of  the  wick.  The  kerosene 
should  contain  no  foreign  matter,  should  be  composed 
entirety  of  hydrocarbons,  should  contain  no  acids  or  products 
of  careless  refining,  and  should  be  quite  free  from  ash. 
The  colour  is  usually  considered  a  point  of  some  importance, 
but  this  is  largely  a  matter  of  taste. 

From  the  point  of  view  of  a  fuel  for  internal  combustion 
motors,  kerosenes  have  lower  calorific  powers  per  unit 
weight  than  benzines  derived  from  the  same  crude  oil. 
If  purchased  by  the  unit  of  volume,  however,  the  advantage 
lies  with  the  kerosene,  owing  to  the  preponderating  effect 
of  the  specific  gravity. 


Sp.  gr. 

B.Th.U.'s  per  Ib. 

B.Th.U.'s  per  gallon. 

Kerosene 
A  motor  spirit 

o'Sio 
0705 

18,900 
I9,I30 

153,000 
134,900 

It  would  appear,  therefore,  that  kerosene  is  the  more 
efficient  motor  fuel  when  purchased  by  the  unit  of  volume. 
It  must  be  remembered,  however,  that  the  detonation 
point  of  kerosenes  is  much  lower  than  that  of  benzines 
generally,  as  a  consequence  of  which  they  can  be  used  only 
in  engines  of  low-compression  ratio,  i.e.  of  low  efficiency. 


256    PETROLEUM  AND   ALLIED  INDUSTRIES 

Moreover,  the  absorption  of  the  kerosene  by  the  lubricating 
oil  is  of  much  greater  consequence  than  in  the  case  of  benzines. 
However,  owing  to  its  low  price,  compared  to  that  of  benzine, 
it  is  economical  in  practice,  being  much  used  as  a  motor  fuel 
for  vaporizing  engines  used  in  propelling  small  boats  and 
for  small  land  power  plants. 

Emulsions  of  kerosenes  are  much  used  as  insecticides  for 
spraying  fruit  trees.  The  kerosene  may  be  emulsified  by 
dissolving  a  soap  in  warm  water  and  adding  to  it  kerosene 
in  small  amounts  with  vigorous  stirring.  Whale-oil  soap  is 
a  good  material  for  the  purpose.  Pure  kerosene  delivered 
by  an  efficient  atomizing  jet  may  however  be  used. 


SECTION  C.— GAS   OILS 

THE  so-called  gas  oils  are  distillates  from  petroleum  or 
shale  oils  intermediate  in  character  between  kerosene  and 
light  lubricating  oils.  They  may  be  made  from  any  type  of 
crude,  either  as  direct  distillates  or  as  by-products  from 
some  subsidiary  operation.  For  example,  as  a  residue 
from  the  redistillation  of  a  heavy  kerosene  distillate,  as  a 
filter  oil  from  the  filtration  of  cooled  wax  distillates,  as  a 
distillate  from  the  concentration  down  of  lubricating  oil 
distillate,  and  as  a  distillate  from  the  destructive  distillation 
of  an  oil  down  to  coke. 

Gas  oils  form  a  loosely  defined  class  of  products,  as  is 
to  be  expected  from  the  fact  that  their  main  use  is  as  fuels 
for  certain  types  of  internal  combustion  motors,  for  thinning 
down  viscous  residual  oils,  as  a  basic  material  for  most 
cracking  processes,  for  gas  enriching  and  for  many  purposes 
of  minor  importance,  such  as  insecticides  and  so  forth. 

As  fuel  oils  the  flash-point  must  lie  above  the  usual  legal 
limits,  65°  C.  or  80°  C.  as  the  case  may  be.  The  viscosity 
of  gas  oils  is  always  so  low  as  to  give  no  trouble  in  this  respect. 
Their  calorific  value  will  depend  somewhat  on  the  nature  of 
the  crude  from  which  they  have  been  manufactured,  as  the 
hydrogen/carbon  ratio  is  not  constant.  The  variation  is, 
however,  comparatively  slight.  The  average  net  calorific 
value  of  a  gas  oil  may  be  taken  as  9800  to  10,200  calories. 
The  specific  gravity  of  gas  oils  may  vary  from  0-850  to  0*920, 
the  percentage  boiling  below  300°  C.  may  vary  very  consider- 
ably from  a  few  percentages  to  70  or  more.  Gas  oils  being 
distillates  should  contain  no  asphaltic  matter  insoluble  in 
petroleum  ether  of  sp.  gr.  0*645,  and  should  leave  only  a 
very  small  percentage  of  coke  (say  0*5  per  cent.)  on  being 
p.  257  17 


258    PETROLEUM  AND  ALLIED  INDUSTRIES 

distilled  to  dryness  in  a  crucible.  (This  test  should  be 
carried  out  under  definite  conditions  as  laid  down  by 
Conradson.) 

Gas  oils  are  rarely  used  as  fuels  for  direct  combustion 
under  boilers  or  in  furnaces,  as  thicker  residual  fuels  serve 
this  purpose  equally  well  and  are  cheaper.  They  are, 
however,  largely  used  in  internal  combustion  motors  of  the 
semi-diesel  type  in  land  installations,  and  in  diesel  engines 
of  the  marine  type.  Diesel  engines  will  burn  residual  fuels 
with  success,  but  as  more  frequent  cleaning  of  the  valves 
is  then  necessary,  gas  oils  find  more  favour  for  marine  use 
where  long  periods  of  running  without  enforced  shut-downs 
are  necessary. 

The  following  table  gives  a  few  representative  analyses 
of  various  gas  oils  : — 


Per  cent. 

boiling  up 

Flash-point. 

to 

°c. 

Gross  calorific 

Sp.  gr.  15    C. 

P  M   °C 

250° 

300° 

per  gram. 

A 

0-848 

85 

6 

52 

10,980 

B 

0-860 

66 

18 

56 

10,900 

C 

0-863 

73 

13 

57 

II,OOO 

D 

0-865 

75 

12 

48 

10,600 

E 

0-895 

65 

15 

46 

~ 

Oils  derived  from  the  distillation  of  coal  tars  may  also 
be  used  for  diesel  engines,  but  as  their  ignition  temperatures 
are  lower  engines  when  running  on  such  oils  are  usually 
fitted  with  a  pilot  ignition  jet,  by  means  of  which  a  little 
petroleum  oil  is  injected  into  the  cylinder  immediately  before 
the  main  charge  of  tar  oil  in  order  to  act  as  a  primer.  The 
calorific  value  of  such  tar  oils  is  about  20  per  cent,  lower  than 
that  of  petroleum  gas  oils  owing  to  the  presence  of  oxygenated 
bodies  such  as  the  higher  homologues  of  phenol. 

Tar  oil  for  diesel  engine  use  should  comply  with  the 
following  specification : — 

i.  Must  not  contain  more  than  2  per  cent,  of  solid 
constituents  insoluble  in  xylene. 


GAS  OILS 


259 


2.  Ash  must  not  exceed  cro8  per  cent. 

3.  Water  not  to  exceed  2*5  per  cent. 

4.  Coking  value  not  to  exceed  3  per  cent. 

5.  The  oil  must  be  a  distilled  product. 

A  few  typical  analyses  of  tar  oils  are  given  herewith 
(Moore,  "  liquid  Fuels  for  Internal  Combustion  Engines  "). 


Oil. 

Sp.  gr.  20°  C. 

Gross  calorific 
value.     Calo- 

Flash-point 
closed. 

Sulphur  per 

Tar  acids. 

ries  per  gram.  1       Gray. 

Horizontal  retort 

tar  oil 

1-049 

9191 

93°  C. 

0-65 

14 

Vertical      retort 

tar  oil 

1-016 

9189 

88°  C. 

0-49 

28 

Blast  furnace  tar 

oil      

0-903 

9992 

70°  C. 

0-28 

23 

The  tar  oils  usually  employed  for  diesel  engine  work 
are  the  creosote  and  anthracene  oils.  The  naphthalene  and 
anthracene  may  be  removed,  but  there  is  no  necessity  for 
tin's  procedure  as  it  is  an  easy  matter  to  keep  the  oil  liquid 
by  warming  the  feed  tank. 

Gas  oils  are  also  extensively  used  for  the  making  of  gas 
for  the  enriching  of  water  gas,  which  is  now  so  largely  used 
to  supplement  coal-gas  supplies.  The  plant  used  for  this 
purpose  consists  of  four  parts,  viz.  the  generator,  carburettor, 
superheater,  and  scrubber.  The  operation  of  such  plants  is 
always  intermittent.  During  the  "  blowing  period  "  air  is 
blown  through  the  coke  in  the  generator  A  (Fig.  41), 
so  as  to  allow  partial  combustion;  secondary  air  is 
also  admitted  into  the  carburettor  B,  which  is  filled  with 
checker  brickwork,  the  combustion  of  the  gases  being 
here  completed.  The  heated  gases  then  pass  into  the 
superheater  C,  where  the  temperature  may  be  controlled 
if  desired  by  admission  of  extra  air.  The  products  of 
combustion  then  pass  into  the  stack  by  the  valve  D.  When 
the  generator  and  carburettor  are  both  thoroughly  well 
heated  and  the  temperature  of  the  superheater  brought 
up  to  about  from  650°  to  700°  C.,  the  air  supply  is  shut  off, 


260    PETROLEUM  AND  ALLIED  INDUSTRIES 

steam  is  blown  into  the  generator  and  the  valve  D  closed  so 
as  to  direct  the  gases  through  the  scrubbers  to  the  gas- 
holders. The  "  blue  "  gas,  a  mixture  of  carbon  monoxide 
and  hydrogen  thus  formed  on  passing  through  the  carburettor, 
comes  into  contact  with  a  spray  of  gas  oil,  which  is  there 
vaporized.  On  passing  through  the  superheater,  the  oil 
vapours  are  cracked  into  permanent  gases,  a  certain  amount 
of  tar  being  also  formed.  As  the  temperature  falls  owing  to 
the  reaction  between  steam  and  carbon  being  endothermic, 
at  a  certain  point  it  is  necessary  to  stop  the  process  and 


LOWE 


FIG.  41. 


revert  to  blowing  again  in  order  to  restore  the  temperatures 
of  the  generator,  carburettor,  and  superheater.  As  a  general 
rule  the  blowing  period  occupies  from  three  to  five  minutes, 
the  gas-making  period  from  two  to  four. 

Gas  oil  is  also  used  for  the  manufacture  of  illuminating  gas 
which  is  used  alone,  e.g.  for  lighting  railway  carriages.  For 
the  making  of  gas  for  such  purposes,  the  gas  oil  is  allowed 
to  drop  slowly  into  retorts  made  of  cast  iron  kept  at  a 
moderately  red  heat. 

In  practice  it  has  been  found  that  for  gas-making  purposes 
gas  oils  derived  from  paraffin  base  petroleums  are  best,  as 


GAS  OILS  261 

they  give  the  maximum  yield  of  gas.  Those  containing 
unsaturated  straight  chain  hydrocarbons  are  less  efficient, 
and  those  containing  aromatics  in  quantity  very  much 
less  so. 


GENERAL   REFERENCES   TO   PART   VIIL,    SECTION   C. 

Diesel  Engine  Users  Association  reports. 

Moore,   "  Liquid   Fuels  for  Internal  Combustion  Engines."     Crosby, 
Lockvvood  and  Son. 

Schenker,  "  Combustibles  pour  Moteurs  Diesel."     Dunod,  Paris. 


SECTION  D.— FUEL   OILS 

L  oils  derived  from  petroleum  and  shale  oils  show  great 
variation  in  character  according  to  the  nature  of  the  crude 
from  which  they  are  derived,  and  the  method  of  manufac- 
ture. If  oils  derived  from  coal  and  low-temperature  tars 
be  included,  the  variation  in  character  is  even  greater. 
Fuel  oils  may  be  divided  broadly  into  two  main  classes, 
viz.  distilled  and  residual  oils. 

The  distilled  oils  include  the  gas  or  solar  oils,  which 
from  a  fuel  point  of  view  are  generally  similar  in  character 
from  whatever  type  of  crude  they  be  manufactured.  These 
distilled  fuel  oils  have  been  dealt  with  in  the  last  section. 

Residual  Fuel  Oils  are  produced  in  the  main  from 
asphaltic  or  naphthenic  base  crudes,  being  in  many  cases 
merely  the  residues  left  after  the  benzine  and  kerosene 
fractions  have  been  "  topped  "  or  "  skimmed  "off.  Many 
such  crudes  yield  80  per  cent,  or  more  of  fuel  oils,  whereas 
the  wax  or  paraffin  base  crudes,  which  are  usually  more 
completely  worked  up,  yield,  as  a  rule,  only  from  10  to  40 
per  cent. 

There  are  no  hard-and-fast  or  even  generally  accepted 
specifications  to  which  fuel  oils  must  conform,  as  in  the 
case  of  the  lighter  constituents  of  petroleum.  Regulations 
generally  demand  a  minimum  flash-point  of  65°  or  80°  C., 
but  are  not  exacting  in  other  respects. 

The  properties  to  be  looked  for  in  a  liquid  fuel  depend  to 
a  great  extent  on  the  purposes  for  which  and  the  conditions 
under  which  it  is  to  be  used.  Residual  fuel  oils  may  be 
used  in  many  cases  as  diesel  oils,  particularly  for  land 
installations  where  the  plants  run  intermittently,  oppor- 
tunities for  frequent  cleaning  being  thus  afforded.  Even 

262 


FUEL  OILS  263 

the  most  viscous  asphaltic  fuels  may  be  used  with  satisfac- 
tion in  diesel  engines,  indeed  coal  tars  may  so  be  used, 
but  the  preference  is  given  naturally  to  distilled  oils  of  the 
gas-oil  type.  Many  diesel  oil  users  specify  a  maximum 
coking  value  of  about  4  per  cent.,  a  figure  which  excludes 
many  residual  oils,  the  coking  values  of  which  may  be  as 
high  as  10  per  cent,  or  more.  Tars,  moreover,  usually 
contain  varying  percentages  of  free  carbon  according  to 
the  method  of  manufacture,  from  about  3  per  cent,  for  low- 
temperature  up  to  20  per  cent,  for  high-temperature  tars. 
A  coal  tar  suitable  for  land  diesel  engine  use  might  have  a 
specification,  sp.  gr.  below  ri2  ;  ash,  below  0*08  per  cent.  ; 
water  less  than  2  per  cent. ;  free  carbon,  not  above  6  per 
cent. ;  coke  value,  not  above  10  per  cent. ;  calorific  value, 
at  least  9100  calories  (J.S.C.I.,  September  15,  1919). 

Liquid  fuels  for  furnace  use  may,  however,  be  allowed 
much  greater  latitude  in  properties.  A  practical  difficulty 
arises  from  the  high  asphaltic  (and/or  wax)  content  of  many 
fuels  bringing  about  a  high  viscosity  and  congealing  point. 
If  arrangements  can  be  made  for  heating  the  oil  then  pumping 
difficulties  disappear.  Perfect  combustion  can  in  all  cases, 
however,  be  attained  if  the  temperature  of  the  fuel  oil  fed  to 
the  burners  is  sufficiently  high.  Specifications  for  liquid  fuels 
are  often  laid  down  by  large  consumers  and  government 
departments,  limiting  the  viscosity,  sulphur  content,  and  so 
forth. 

The  British  Admiralty,  for  example,  demand  a  viscosity 
not  exceeding  IOQO  seconds  Redwood  II.  at  o°  C.,  a  flash-point 
of  80°  C.  and  a  sulphur  content  not  exceeding  3  per  cent. 
The  United  States  navy  limit  the  specific  gravity  to  the 
range  0-85  to  0*96,  the  sulphur  content  to  not  exceeding 
i '5  per  cent.,  and  the  viscosity  to  not  exceeding  140  seconds 
Saybolt  Furol  at  70°  F.  (2i'i°  C.).  They  also  demand  a 
calorific  value  of  not  less  than  10,000  calories  per  gram,  taking 
10,250  as  the  standard  and  paying  a  bonus  or  deducting  a 
penalty  as  the  fuel  oil  supplied  has  a  calorific  value  above  or 
below  this  value.  France  demands  a  minimum  flash-point 
of  93°  C.  and  Italy  100°  C.  for  fuel  for  naval  use. 


264    PETROLEUM  AND  ALLIED  INDUSTRIES 

The  characters  of  a  few  residual  fuel  oils  taken  at  random 
given  herewith,  will  illustrate  the  great  diversity  of  character 
of  these  oils. 


Fuel  oil. 

Sp.  gr. 
@  15°  C. 

Vise.  R.  1. 
@  100°  F. 

Flash- 
point °C. 

Sulphur 
per  cent. 

Gross  calorific 
value.    Calories 
per  gram. 

Texas 

0-889 

74 

I05 

0-6 

IO,8oo 

Persia 

0-899 

150 

88 

I  '5 

10,550 

Borneo 

0-913 

4i 

80 

o-i 

10,500 

Texas 

0-917 

204 

99 

— 

10,700 

Trinidad 

0-947 

450 

86 

— 

— 

Mexican 

0*955 

1360 

71 

2-9 

10,450 

Mexican 

0-961 

2500 

75 

3'7 

IO.2IO 

Venezuela 

0-963 

5000 

83 

2-4 

IO,2OO 

Texas 

Q'973 

4850 

86 

0-9 

10,400 

A  very  complete  list  of  fuels  and  their  properties  is  given 
in  the  Mechanical  World  for  April  2,  1920,  to  which  the 
reader  is  referred. 

The  various  tars  derived  from  the  distillation  of  coals 
under  various  conditions  and  of  lignite,  peat,  wood,  etc., 
may  also  be  used  as  liquid  fuels.  For  diesel  engine  use 
they  cannot  compare  with  the  petroleum  fuels.  The  diffi- 
culty of  ignition  may  be  overcome  by  the  use  of  a  pilot  jet 
as  described  under  tar  oils  (p.  258),  but  the  presence  of  free 
carbon  in  such  tars  is  a  severe  handicap,  as  this  gives  rise 
to  much  trouble  with  the  exhaust  valves.  The  removal  of 
the  free  carbon  from  such  tars  is  difficult  and  hardty  an 
economic  proposition.  The  relatively  high  ash  content  also 
militates  against  their  successful  use. 

When  tars  are  used  in  furnace  work  the  objections 
mentioned  above  naturally  largely  disappear.  The 
high  specific  gravity  of  the  tars  makes  the  separation 
of  water  difficult,  and  the  low  calorific  value  must  always 
remain  an  objection,  which,  however,  may  be  nullified 
by  price  of  the  tars  in  relation  to  fuels  of  higher  calorific 
value. 

Analyses  of  several  types  of  tars  are  herewith  given 
(Moore,  "  liquid  Fuels  for  Internal  Combustion  Engines  "). 


FUEL  OILS 


265 


Tar. 

Sp.  gr. 
@I5°C. 

Elementary  Analysis. 

Ash. 

Coke. 

Net  calorific 
value.  Calories 
per  gram. 

Free 
carbon 
per 
cent. 

C. 

H. 

S. 

Horizontal 

1 
I 

retort     .  . 

I'lSo 

91-5 

5'2 

0'5 

O'2O 

24-0 

8645 

18-2 

Vertical    re- 

tort 

1-089 

88-0 

6-8 

0-6 

0-03 

6-1 

8664 

17 

Simon-Carve 

coke  oven 

I'OQO 

88-1 

5'6 

0-2 

0-07 

6-0 

9261 

traces 

Low  temper- 

ature car- 

bonization 

1-058 

85-8 

8-1 

0-09 

O'll 

8-2 

8776 

2-2 

Water  gas.. 

i'°54 

92*2 

6-8 

0-6 

trace 

187 

8647 

6-8 

Blast 

furnace  .  . 

1-172 

89-5 

575 

0-84 

0-36 

23H 

8288 

9'5 

Methods  of  Burning  Liquid  Fuels. — liquid  fuels  are 
usually  burnt  under  furnaces  by  one  of  three  methods,  the 
choice  of  method  depending  upon  conditions,  viz.  (a)  injection 
or  atomizing  by  means  of  steam,  (b)  by  means  of  compressed 
air,  (c)  by  means  of  pressure  only.  Atomizing  jets  may  be 
divided  into  three  main  groups  :  (i)  those  in  which  the 
atomizing  is  effected  by  the  simple  impact  of  a  stream  of 
oil  and  air  or  gas,  (2)  those  of  the  injector  type,  and  (3)  those 
of  the  direct  spray  type,  in  which  no  spraying  agent  is 
emplo3^ed,  the  oil  being  merely  forced  under  pressure  through 
a  suitable  jet.  Innumerable  forms  of  burner  have  been 
devised  (Report  of  the  United  States  Liquid  Fuel  Board, 
1904),  the  description  of  which  lies  beyond  the  scope  of  this 
work.  The  steam  injection  system  is  very  simple  and  is 
much  used  for  land  installations.  An  objection  to  this 
system  is  the  fact  that  about  6  per  cent,  of  the  steam  raised 
is  used  for  spraying  the  liquid  fuel  For  this  reason  this 
arrangement  is  rarely  if  ever  installed  in  sea-going  vessels. 
The  compressed  air  system  is  not  much  used  as  the  installa- 
tion of  auxiliary  compressor  plant  is  necessary.  For  small 
installations  or  where  compressed  air  is  available  this  method 
of  injection  is  useful,  as  it  is  very  easy  to  manipulate.  The 
pressure  jet  system  is  the  most  economical  in  practice,  the 
steam  required  for  pumping  and  heating  the  oil  amounting 


266    PETROLEUM  AND  ALLIED  INDUSTRIES 

to  only  about  2  per  cent,  of  that  generated.  The  system 
may  be  applied  to  even  the  thickest  and  heaviest  oils  provided 
that  the  oil  is  heated  to  a  sufficiently  high  temperature  before 
injection.  If  this  temperature  be  too  low  incomplete 
combustion  with  production  of  much  smoke  results. 

The  advantages  presented  by  burning  liquid  fuels  in 
place  of  coal  are  very  great.  The  calories  per  unit  weight 
are  considerably  greater  in  the  ratio  of  approximately  i  "6  to 
i,  so  that  with  certain  prices  the  actual  number  of  calories 
per  unit  cost  may  be  greater.  If,  however,  this  is  not  the 
case,  there  are  so  many  collateral  advantages  on  the  side  of 
oil  that  the  higher  cost  per  calorie  is  usually  more  than 
completely  counterbalanced.  Among  such  advantages  may 
be  enumerated  the  following :  Less  room  required  for 
storage  ;  less  difficulty  and  cost  in  transport  and  handling  ; 
more  uniformity  in  fuel ;  absence  of  ash,  cleaning  of  furnaces 
and  costs  of  removal  of  ashes  thus  being  avoided  ;  less  wear 
and  tear  on  the  plant ;  greater  efficiency  of  the  boilers, 
resulting  in  lower  maintenance  costs,  and  lower  capital 
outlay  for  a  definite  steam-raising  capacity,  or  increase  in 
capacity  for  an  existing  plant ;  greater  flexibility  and  easier 
control  in  running,  and  very  much  reduced  labour  charges, 
not  to  mention  such  minor  advantages  as  absence  of  smoke 
and  general  cleanliness. 

When  applied  to  marine  use  further  advantages  result 
in  :  the  superior  evaporative  power  per  unit  weight  of 
fuel  carried,  thus  ensuring  greater  radius  of  action,  or  less 
weight  of  fuel  necessary  for  a  given  voyage,  thus  allowing 
more  cargo  space,  and  ease  of  bunkering  and  consequent 
saving  of  valuable  time. 

Nevertheless,  to  quote  Beeby  Thompson,  "  From  an 
economic  point  of  view,  the  burning  of  oil  under  boilers  can 
only  be  regarded  as  a  wanton  waste  of  the  world's  resources, 
as  each  pound  of  oil  consumed  under  boilers  is  capable  of 
yielding  four  or  five  times  the  power  if  applied  in  accordance 
with  modern  methods,"  i.e.  in  internal  combustion  engines. 

As  liquid  fuel  presents  such  numerous  advantages  over 
coal,  particularly  for  sea-going  vessels,  the  world's  shipping 


FUEL  OILS  267 

is  rapidly  turning  to  the  use  of  oil,  indeed  the  world's  navies 
have  already  adopted  it  as  their  standard.  Whereas  10*5  per 
cent,  of  the  world's  shipping  tonnage  in  1918-19  used  oil  fuel 
under  boilers,  16-3  per  cent,  used  it  in  1919-20  (The  Naval 
Annual,  1920-21,  lyondon,  p.  180).  During  the  last  few 
years  bunkering  stations  in  great  number  have  been  con- 
structed by  the  leading  oil  companies,  so  that  now  ample 
supplies  are  ensured  at  numerous  points  on  the  great  trade 
routes  throughout  the  world. 


GENERAL  REFERENCES  TO   PART  VIII.,  SECTION   D. 

Baillie,  "  Fuel  Oil  Burning,"  J.R.S.A.,  vol.  69,  1921,  p.  231. 

Brame,  "  Liquid  Fuel  and  its  Combustion,"  J.I.P.T.,  1917,  p.  194. 

Brewer,  "  Efficient  Handling  of  Fuel  Oil,"  Power,  1921,  January-March. 

Dunn,  "  Industrial  Uses  of  Fuel  Oil."  Technical  Publishing  Co.,  San 
Francisco. 

Moore,  "  Liquid  Fuels  for  Internal  Combustion  Engines."  Crosby, 
Lockwood  and  Son. 

North,  "  Oil  Fuel."     C.  Griffin  and  Co. 

Sothern,  "  Oil  Fuel  Burning  in  Marine  Practice."  Munro  and  Co., 
Glasgow. 


SECTION  E.— PARAFFIN  WAX 

ALTHOUGH  paraffin  wax  cannot  be  regarded  as  one  of  the 
main  products  of  petroleum  it  is,  nevertheless,  produced  in 
large  quantities,  not  only  in  the  United  States,  where 
production  for  1920  amounted  to  152,000  tons,  but  also  in 
the  East  Indies,  Burmah,  Rumania,  Galicia,  Mexico,  and 
elsewhere.  It  is,  moreover,  produced  in  quantities  from 
shale  oil,  as  in  Scotland,  and  from  the  distillation  of  lignite 
in  Thuringia. 

Paraffin  wax,  together  with  ceresin  and  montan  wax, 
finds  its  chief  use  for  the  manufacture  of  many  articles  for 
which  otherwise  the  more  expensive  bees-  or  other  wax 
would  be  used.  In  many  cases,  too,  new  industries  involving 
the  use  of  paraffin  wax,  have  been  developed.  A  good 
example  of  the  replacement  of  beeswax  by  paraffin  is 
afforded  by  the  "  batik  "  industry  in  Java.  Fabrics  are 
dyed  by  the  natives  by  first  covering  the  portions  of  the 
surface  which  are  not  to  be  dyed  by  a  layer  of  batik  wax, 
applied  in  the  melted  state  by  hand,  by  means  of  a  very 
small  kettle,  and  then  immersing  the  material  in  the  dye. 
After  dyeing,  the  wax  is  removed  by  hot  water  and  used 
again.  Beeswax  was  at  one  time  almost  universally  used 
for  this  industry,  but  it  has  been  largely  replaced  by  substi- 
tutes composed  in  the  main  of  paraffin  wax,  blended  with 
such  substances  as  carnauba  wax,  montan  wax,  japan 
wax,  resins  and  the  like.  Many  such  varieties  of  vegetable 
or  animal  wax  substitutes  are  made.  Paraffin  wax  also 
enters  largely  into  the  composition  of  polishes  for  floors, 
leather,  etc.  Large  quantities  are  used  in  the  electrical 
industries  for  insulating  purposes,  often  directly,  often  in 
admixture  with  resin,  tallow,  etc.,  for  cable  work.  The  use 

268 


PARAFFIN  WAX  269 

of  paraffin  wax  for  waterproofing  paper  for  packing  purposes, 
for  making  jam  pots  and  the  like,  is  now  the  basis  of  a 
considerable  industry.  It  is  so  used  in  the  making  of 
washable  wall-papers,  for  waterproofing  cartridges,  in  the 
waterproofing  of  chrome  leather.  It  also  plays  an  important 
part  in  the  waterproofing  and  finishing  of  textile  fabrics. 
For  making  rainproof  material,  a  solution  of  paraffin  wax 
in  benzine  or  other  volatile  solvent  is  sprayed  on  to  the 
cloth.  In  conjunction  with  ceresin  and  soap,  together  with 
starch  and  filling  material,  it  is  used  for  glazing  certain 
fabrics  by  hot  calendaring.  It  is  also  used  in  laundry  work 
for  imparting  a  high  gloss  to  collars,  etc. 

It  is  also  used  as  a  convenient  base  for  many  ointments 
for  medical  use  in  admixture  with  wool  fats  and  oils,  and  in 
quite  another  direction  for  surgical  use  as  a  dressing  to 
exclude  air  and  even  in  place  of  plaster  of  Paris  for  splints. 
For  many  other  minor  purposes  such  as  manufacture  of 
crayons,  sealing  waxes,  etc.,  quantities  are  used. 

By  far  the  largest  quantities,  however,  are  used  for  the 
manufacture  of  candles,  nightlights  and  the  like.  Candles 
are  made  by  casting  in  moulds  made  of  an  alloy  of  tin  and 
lead,  the  wick  being  placed  in  situ  before  running  in  the 
wax.  These  moulds  are  grouped  together  in  machines 
which  may  contain  200  or  more  moulds.  Candles  may  be 
made  of  pure  paraffin,  but  it  is  usual  to  employ  mixtures, 
because  pure  paraffin  has  a  tendency  to  stick  to  the  moulds, 
and,  moreover,  candles  of  pure  paraffin  soften  too  readily 
on  exposure  to  only  moderate  temperatures.  Stearine,  a 
mixture  of  stearic  and  palmitic  acids  prepared  by  the 
splitting  of  certain  fats,  is  mostly  used  for  this  purpose, 
grades  of  melting  point  55°  C.  being  usually  selected. 
Mixtures  of  stearine  and  paraffin  have  always  melting  points 
lower  than  those  of  the  constituents,  but  in  spite  of  this 
they  stand  up  better  to  heat  and  less  readily  become  plastic. 
The  real  advantage  of  adding  stearine  is  this  stiffening 
effect.  The  white  marble-like  appearance  caused  by  the 
addition  of  stearine  is  of  minor  importance ;  nevertheless, 
attempts  have  been  made  to  imitate  this  by  the  addition 


270    PETROLEUM  AND  ALLIED  INDUSTRIES 

of  small  percentages  of  such  substances  as  /3-naphthol. 
Candles  may  be  coloured  by  the  use  of  certain  aniline  dyes 
which  are  slightly  soluble  in  paraffin  wax  or  stearin, 
e.g.  methyl  violet,  malachite  green,  quinoline  yellow,  and 
so  forth.  Although  the  quantities  used  are  so  minute, 
colourless  candles  always  burn  better. 

The  wick  plays  a  very  important  part,  and  great  care 
must  be  bestowed  on  its  manufacture.  A  wick  must  be 
"  self -snuffing,"  i.e.  it  must  bend  over  so  as  to  project  into 
the  outer  oxidizing  atmosphere  of  the  flame,  and  must  be 
impregnated  with  certain  chemicals  to  enable  it  to  burn  to 
a  light  powdery  non-coherent  ash.  The  former  is  attained 
by  weaving  the  wick  with  one  set  of  strands  under  greater 
tension  than  the  others,  the  latter  by  impregnating  the 
wick  with  such  salts  as  potassium  chlorate,  ammonium 
nitrate,  ammonium  phosphate.  In  addition  to  being  used 
for  the  direct  manufacture  of  wax  matches,  paraffin  of  low 
melting  point,  about  47°  C.  is  used  for  impregnating  the  tips 
of  wooden  matches. 


GENERAL   REFERENCES   TO   PART  VIII.,   SECTION   E. 

Campbell,  "  Petroleum  Refining."     C.  Griffin  and  Co. 
Graefe,  "  Die  Braunkohlenteer-Industrie."     W.  Knapp,  Halle. 
Gregorius,  "  Mineral  Waxes."     Scott,  Greenwood  and  Son. 
Lamborn,   "  Modern  Soaps,  Candles,   and   Glycerin."     Crosby,  Lock- 
wood  and  Son. 

Scheithauer,  "  Shale  Oils,  and  Tars."     Scott,  Greenwood  and  Son. 


SECTION  F.— LUBRICATING  OILS 

THE  subject  of  lubrication  generally,  and  more  particularly 
that  of  the  relation  between  the  chemical  and  physical 
properties  of  an  oil  and  its  practical  lubricating  value,  is 
one  of  great  difficulty.  Much  has  been  written  on  the  subject, 
but  there  is  a  great  lack  of  concrete  fundamental  data,  so 
that  the  basic  problems  are  still  far  from  being  solved. 

Up  till  quite  recent  times,  lubrication  presented  no 
difficult  problems.  Vegetable  oils  and  fats  were  used,  sperm 
oils  for  light-running  machinery,  rape,  castor,  and  lard  oils 
for  heavier  work,  and  tallow  for  the  heaviest.  As  modern 
high-speed  machinery  developed  and  as  the  demand  for 
lubricating  oil  increased,  mineral  lubricating  oils  began  to 
come  into  use,  naturally  first  by  blending  with  sperm  and 
other  fatty  oils.  Thus  according  to  Parish  (Chemical  Age, 
New  York,  1922,  p.  61),  the  lubricating  oil  business  developed 
along  most  complicated  lines,  so  that  "  in  a  decade  the  lubri- 
cating practice  of  the  world  was  one  jumbled  mass  of  dis- 
associated facts  due  to  the  practice  of  producing  a  compara- 
tively few  number  of  oils  at  the  refinery  and  of  compounding, 
mixing,  and  branding  an  immense  and  complicated  number 
of  oils,  many  of  them  finally  being  used  for  the  lubrication 
of  the  same  class  of  machinery,  as,  for  instance,  high-speed 
machinery  working  under  about  the  same  mechanical 
conditions,  but  being  lubricated  with  a  great  number  of 
different  kinds  of  compounds  and  mixtures  sold  under  a 
multitude  of  names,  all  descriptive  of  the  machine  on  which 
the  oil  was  intended  to  be  used."  In  this  manner  the 
lubricating- oil  trade  developed,  and  in  this  manner  it  exists 
to-day.  There  is,  however,  a  tendency  to  improvement. 

271 


272    PETROLEUM  AND  ALLIED  INDUSTRIES 

The  futility  of  present  methods  is  being  recognized,  the 
number  of  brands  is  being  reduced  and  efforts  are  being  made 
to  study  the  problems  and  acquire  data  of  real  value.  With 
the  modern  developments  of  machinery  new  lubricating 
problems  have  arisen,  such  as  the  lubrication  of  superheated 
steam  cylinders,  and  internal  combustion  engines  of  various 
classes.  Such  special  conditions  call  for  certain  types  of 
oil  regarding  which  a  good  deal  of  empirical  knowledge 
has  been  accumulated.  In  all  cases  of  lubrication  the 
design  and  condition  of  the  surfaces  to  be  lubricated  play 
much  the  most  important  part.  Bearings  of  the  Michell 
type  are  so  nearly  perfect  that  the  character  of  the  oil  used 
is  of  quite  secondary  importance. 

The  physical  property  most  generally  considered  in 
relation  to  lubricating  value  is  the  viscosity.  In  the  case  of 
lightly  loaded  spindles  running  at  high  speed  the  viscosity  or 
internal  friction  of  the  oil  is  the  factor  of  prime  importance, 
so  in  dealing  with  such  cases  there  is  little  difficulty.  In  the 
case  of  heavily  loaded  bearings,  however,  the  problem  is 
one  of  the  capability  of  the  oil  of  forming  a  thin  film  and  of 
maintaining  this  film  without  breaking  down  under  conditions 
of  great  stress. 

According  to  Ivangmuir  the  spreading  of  the  oil  in  a  film 
only  one  molecule  thick  depends  on  a  definite  chemical 
attraction  between  the  metal  and  the  oil.  According  to 
this  view  unsaturated  compounds  should  be  better  lubricants 
than  saturated.  This  is,  in  fact,  borne  out  by  the  work  of 
Wells  and  Southcombe  on  the  effect  of  the  addition  of  small 
percentages  of  fatty  acids  to  mineral  lubricating  oils  (J. S.C.I., 
vol.  39,  p.  5iT).  This  has  led  to  efforts  to  correlate  the  lubri- 
cating power  of  an  oil  with  its  surface  tension  relative  to 
metals,  a  difficult  problem  which  has  not  yet  been  successfully 
attacked.  Holde  (Chem.  Ztg.,  1921,  p.  3)  states  that  mineral 
lubricating  oils  have  on  the  average  lower  surface  tensions 
than  fatty  oils.  He  takes  the  product  of  the  surface  tension 
of  an  oil  in  air  with  the  cosine  of  the  angle  of  contact  as  a 
measure  of  the  affinity  of  an  oil  for  the  metal  to  be  lubricated. 
He  also  confirms  Wells'  and  Southcombe's  observations, 


LUBRICATING  OILS 


273 


Oils  derived  from  petroleum  have  largely  replaced  the 
vegetable  and  animal  oils  once  generally  used.  Mineral 
oil  lubricants  can  be  manufactured  in  great  variety,  ranging 
from  the  thinnest  spindle  oils  more  limpid  than  sperm  oil 
to  the  thickest  oils  more  viscous  than  castor.  The  viscosities 
of  mineral  oils  fall  off  more  rapidly  with  increase  of  tempera- 
ture than  do  those  of  fatty  oils,  this  phenomenon  being  much 
less  marked,  however,  at  temperatures  over  40°  C.  (Archbutt 
and  Deely,  "Lubrication  and  Lubricants,"  p.  191).  The 
more  viscous  the  oil,  the  more  marked  is  the  change  of 
viscosity  with  temperature.  Woog  (Comptes  rendus,  1921, 
P-  3°3)  found  (cryoscopically)  that  the  mean  molecular 
volume  of  a  fatty  oil  was  much  less  than  that  of  a  mineral 
oil  of  the  same  viscosity. 

Of  the  chemistry  of  mineral  lubricating  oils  little  is 
known.  They  consist  of  hydrocarbons  of  high  molecular 
weight,  consequently  the  difficulty  of  isolating  any  group 
of  individuals  and  still  more  so  of  elucidating  their  constitu- 
tion is  very  great.  Marcusson  (Chem.  Ztg.,  1911,  pp.  729, 742) 
holds  that  the  constituents  to  which  mineral  oils  chiefly 
owe  their  lubricating  power  are  those  which  do  not  react 
with  formaldehyde  and  sulphuric  acid.  Mabery  ("  Composi- 
tion of  Petroleum  and  its  Relation  to  Industrial  Use," 
Am.  Inst.  of  Min.  and  Met.  Engineers,  February,  1920) 
states  that  hydrocarbons  of  the  general  formula  CnH2n_4  form 
the  constituents  of  the  best  lubricants  it  is  possible  to  prepare 
from  petroleum,  and  that  heavy  petroleums  of  an  asphaltic 
base  contain  these  hydrocarbons  in  large  proportion,  and 
lighter  varieties  in  small  amounts.  He  also  concluded  that 
hydrocarbons  of  the  series  CnH2n+2  had  a  low  lubricating 
value,  and  that  the  lubricating  hydrocarbons  from  Pennsyl- 
vania petroleums  consisted  mostly  of  the  series  C2H2n  and 
CnH2n_2.  Aisinmann  (J. S.C.I.,  1895,  p.  2812)  states  that  the 
lubricating  oils  of  Baku  are  composed  mainly  of  naphthenes 
and  defines,  but  this  has  been  disputed. 

Unsaturated  hydrocarbons  constitute  20  to  40  per  cent, 
of  most  lubricating  oil  distillates.     They  can  be  and  often 
are   removed   by   treatment    with   concentrated   sulphuric 
p.  18 


274    PETROLEUM  AND  ALLIED  INDUSTRIES 

acid,  as  in  the  ordinary  process  of  refining.  Certain  unsatu- 
rated  hydrocarbons  and  asphaltic  resins,  which  are  probably 
mainly  responsible  for  gumming  and  carbonization  of  oils, 
should  be  removed,  but  it  is  open  to  question  as  to  whether 
the  sulphuric  acid  treatment  does  not  also  remove  desirable 
unsaturated  constituents. 

The  saturated  constituents  are  probably  naphthenic  and 
polynuclear  in  structure,  but  it  is  possible  that  isoparaffins, 
too,  possess  lubricating  properties.  Of  the  influence  or  even 
presence  of  aromatic  hydrocarbons  in  lubricating  oils 
practically  nothing  is  known. 

The  influence  on  the  viscosity  of  lubricating  oils  of  their 
chemical  composition  has  been  studied  by  Mabery  and 
Mathews  (/.  Am.  Chem.  Soc.,  1908,  p.  992),  who  showed 
that  a  low  hydrogen  content  is  related  to  a  high  viscosity. 
Dunstan  and  Thole  (J.I.P.T.,  1918,  p.  191)  consider  that 
"  a  lubricating  oil  should  contain  a  certain  proportion  of 
unsaturated  hydrocarbons,  as  large  a  proportion  as  is 
compatible  with  not  too  much  susceptibility  to  oxidation, 
polymerization,  gumming,  and  reactivity." 

Mineral  lubricating  oils  from  the  point  of  view  of  manu- 
facture fall  into  two  main  groups,  (a)  residual  oils,  and 
(b)  distillate  oils. 

(a)  The  residual  oils  may  be  further  divided  into  two 
classes:  (i)  the  black  axle  oils  which  are  unfiltered  and 
untreated,  made  from  either  naphthene  or  paraffin  base 
crudes  by  concentrating  down  to  the  required  viscosity. 

Typical  analyses  of  such  oils  are — 

A.            B.  c. 

Specific  gravity  at  15°  C.       . .     0*896  0-952  0-955 

Flash-point,  P.M.  °C 230         233  190 

Fire  test  °C . .        280         270  220 

Viscosity,  Kngler,  at  50°  C.    . .        21           24  35 

„     at  100°  C.  . .     3-3  2-7  3-3 

(2)  The  cylinder  stocks  made  from  certain  paraffin  wax 
base  crude  oils,  notably  those  of  the  Appalachian  fields. 
These  cylinder  oils,  which  are  largely  used  for  steam  cylinder 


LUBRICATING  OILS  275 

lubrication  and  for  blending  with  distillate  oils  for  motor 
cylinder  and  other  uses,  are  characterized  by  high  flash-points, 
and  by  a  good  viscosity  curve,  i.e.  a  relatively  less  falling  off 
of  viscosity  with  increase  of  temperature,  than  that  evidenced 
by  other  classes  of  oils.  They  appear  on  the  market  as 
steam-refined  cylinder  stocks  and  as  filtered  cylinder 
stocks,  the  latter  being  obtained  from  the  former  by  nitration 
through  some  form  of  fuller's-earth. 
Typical  analyses  of  cylinder  stocks— 

A.  B.  c.  D. 

Specific  gravity  at  15°  C.    . .    0*890  0-902  0*884  0*892 

Flash-point  P.M.  °C.           . .      265  280  240  260 

Fire  test  °C.              . .          . .      324  320  300  315 

Viscosity,  Engler,  at  50°  C.        27  29  17*5 

100°  C.      4*1  4*1  3*2 

Red  wood  I.  at  100°  F.     —  —  1800 

at  200°  F.  144 

(b)  The  great  majority  of  mineral  lubricating  oils  belong 
to  the  second  category.  The  manufacture  of  these  oils  has 
already  been  described.  They  may  be  further  subdivided 
roughly  into  two  classes,  viz.  (i)  those  derived  from  paraffin 
wax  base  oils,  (2)  those  derived  from  naphthenic  base  oils,  but 
as  crude  oils  vary  so  greatly  oils  of  all  grades  intermediate 
between  these  two  types  are  found.  These  two  classes  of 
oil  differ  to  some  extent  in  their  properties.  For  oils  of  the 
same  viscosity  the  specific  gravity  of  the  naphthenic  oil  is 
the  higher,  and  the  flash-point  the  lower.  Moreover,  oils  of 
the  naphthenic  type  show  a  greater  falling  off  of  viscosity 
with  increase  of  temperature  (Fig.  42). 

It  is  generally  held  that  the  more  gentle  gradient  of  the 
viscosity  curves  of  the  oils  derived  from  paraffin  base  crudes 
is  a  point  in  their  favour,  but  this  view  is  by  no  means 
proved. 

The  viscosities  of  all  lubricating  oils  at  high  temperatures, 
say  200°  C.,  approximate  very  closely  to  each  other.  The 
differences  in  viscosity  of  various  oils  are  more  marked  the 
lower  the  temperature  (Fig.  43). 


LJ 


CO 


20 


3O  5O  1O  SO 

TEMPERflTURE     IN    °C . 


FIG.  42. — Curves  showing  relation  of  viscosity  to  temperature 

for  lubricating  oils :    from  paraffin   base   crudes  ; 

from  naphthene  base  crudes  


1000 


800 


I600 


4.0O 


200 


SOY 


FOR 
R   h 


iOLT  VISC3SITV     CtRVES 


LUBRICRTIMQ     Oll_S 
PTHENE  BflSE    CR 


FROM 

DC. 


100  130  160 

TEMPERflTUPE.T. 


ISO        210 


FIG.  43. — Curves  showing  relation  of  viscosity  to  temperature 
for  four  oils  of  the  same  type. 


LUBRICATING  OILS  277 

The  specific  gravity  of  lubricating  oils  is  a  property 
which  has  no  direct  significance.  Indirectly,  however,  it 
indicates  the  origin  of  the  oil,  as  for  any  definite  viscosity  at 
temperature  t°  the  specific  gravities  of  oils  derived  from  the 
paraffin  wax  base  crudes  are  lower  than  those  of  oils  from 
naphthene  base  crudes. 

The  flash-point  of  a  lubricating  oil  is  usually  specified. 
This  property  perhaps  has  some  significance,  as  an  unduly 
low  flash-point  might  indicate  careless  fractionation  or 
possibly  overheating  during  distillation  with  the  result  that 
cracking  had  taken  place.  This  latter  might  be  taken  to 
indicate  instability  of  the  oil  at  high  temperatures,  and  there- 
fore the  unsuitability  of  the  oil  for  certain  classes  of  work. 
In  general,  however,  the  flash-point  has  no  intrinsic  signifi- 
cance. As  is  the  case  with  specific  gravity  it  may  indicate 
the  origin  of  the  oil ;  on  the  contrary,  it  undoubtedly  bears 
some  relation  to  the  volatility  of  the  oil,  or  the  loss  by 
evaporation  at  high  temperatures,  but  if  such  a  factor  be  of 
importance,  then  it  is  much  better  to  carry  out  a  specific 
test  on  this  point  rather  than  rely  on  inferences  drawn  from 
the  flash-point. 

In  the  case  of  oils  to  be  used  for  the  lubrication  of  internal 
combustion  engines  a  test  which  could  indicate  the  degree 
of  resistance  to  carbonization  in  the  cylinder  would  be  of 
value.  Unfortunately,  no  such  test,  which  gives  reliable 
figures  which  may  be  interpreted  in  terms  of  actual  practice, 
is  known.  The  nearest  approach  to  such  a  test  is  perhaps 
the  coking  test  as  carried  out  by  the  Conradson  method 
(/.  Ind.  and  Eng.  Chem.>  vol.  4,  p.  903). 

Garner  (J.I.P.T.,  1921,  p.  98)  expresses  the  opinion  that 
"  the  rapid  carbonization  of  oil,  i.e.  the  coking  value,  will 
be  a  more  important  factor  in  the  testing  of  lubricating  oils 
for  internal  combustion  engines  than  the  gradual  carboniza- 
tion at  lower  temperatures,"  basing  this  opinion  on  the 
supposition  that  the  major  part  of  the  oil  which  gets  into 
the  combustion  space  is  in  the  form  of  a  fine  spray.  This  is 
very  much  open  to  doubt.  Certainly  the  Conradson  test  does 
not  give  reliable  indications  as  to  the  ease  of  carbonization 


278    PETROLEUM  AND  ALLIED  INDUSTRIES 

in  many  cases  (Circular,  Bureau  of  Standards,  U.S.A., 
No.  99,  "  Carbonization  of  I/ubricating  Oils").  It  is  quite 
possible  that  the  so-called  carbon  deposits  which  form  on 
the  pistons  of  automobile  engines  are  due  to  cracking  of 
the  lubricating  oil,  but  they  may  also  be  due  to  oxidation. 
Waters  has  devised  a  test  (Bureau  of  Standards,  Scientific 
Papers  1532160,  Technologic  Papers  4273,  and  Circular  99) 
based  on  oxidation,  but  so  far  this  test  also  has  not 
yielded  results  comparable  to  those  obtained  in  actual 
practice. 

The  ash  of  lubricating  oils  for  use  in  internal  combustion 
engines  should  naturally  be  as  low  as  possible.  Distilled 
oils  should  yield  no  appreciable  ash  and  filtered  residual 
cylinder  oils  should  not  yield  more  than  0*02  per  cent., 
although  higher  figures  than  these  are  often  found. 

Pure  mineral  oils  should  be  free  from  soaps,  the  presence 
of  which  may  indicate  inefficient  washing  after  the  refining 
process.  The  presence  of  such  soaps  may  give  the  oil  a 
stringy  character,  which  is  usually  objected  to  by  buyers, 
although  it  does  not  necessarily  impair  the  lubricating 
qualities  of  the  oil.  In  certain  cases,  indeed,  aluminium 
oleate  is  added  to  increase  the  consistency,  and  soaps  are 
normal  constituents  of  greases.  Oils  containing  soaps  will 
more  readily  emulsify  with  water  than  will  pure  mineral 
oils.  For  many  purposes,  particularly  in  the  case  of  forced 
feed  systems  of  lubrication  as  in  the  case  of  turbines,  an 
oil  which  will  resist  emulsification,  i.e.  which  has  a  good 
demulsibility,  is  necessaty. 

For  general  lubricating  work  a  very  large  number  of 
lubricating  mineral  oils  are  made,  and  the  number  is  still 
further  increased  by  blends  with  fatty  oils.  For  a  few 
specific  purposes  oils  of  special  character  are  required.  For 
the  general  lubrication  of  marine  engines  heavy  mineral 
oils,  blended  with  from  20  to  30  per  cent,  of  a  blown  vege- 
table oil  such  as  rape,  are  usual. 

For  automobile  cylinder  lubrications  blended  oils,  con- 
taining filtered  cylinder  stock  but  no  fatty  oils,  are  used. 
Such  oils  should  be  resistant  to  carbonization,  but  a  means  of 


LUBRICATING  OILS  279 

satisfactorily  measuring  this  property  in  the  laboratory  is 
still  to  be  devised. 

For  air  compressors  oils  resisting  oxidation  must  be 
selected  and  for  refrigerating  machines  naturally  oils  of 
low  cold  test. 

Oils  for  turbines  should  be  pure  mineral  oils  free  from 
any  trace  of  organic  acid,  so  that  they  resist  emulsifying 
with  water.  A  type  of  oil  not  strictly  a  lubricant,  but  similar 
in  character,  which  may  be  noticed  here  is  transformer  oil. 
Transformer  cases  are  rilled  with  oil,  as  oil  is  a  better  con- 
ductor of  heat  than  air,  and  so  dissipates  more  quickly  the 
heat  generated,  and  for  good  insulation  purposes.  The 
requirements  of  a  good  transformer  oil  are — 

(1)  It  must  have  a  good  dielectric  strength.     It  should 
not  break  down  at  less  than  22,000  volts  when  tested  between 
the  flat  surfaces  of  two  parallel  discs  i  inch  diameter  and 
TJo  inch  apart ;    or  not  less  than  40,000  volts  when  tested 
between  two  12*5  mm.  spheres  5  mm.  apart. 

(2)  It  must  be  quite  free  from  moisture,  as  this  causes 
very  serious  falling  off  in  the  dielectric  strength.     As  little 
as  0*005   Per  cent,   of  water  will   reduce  the  breakdown 
voltage  by  50  per  cent. 

(3)  It  should  have  a  low  viscosity,  about  8°  Bngler  at 
20°  C.  or  2-5°  Engler  at  50°  C. 

(4)  It  should  be  pale  in  colour  consequent  upon  intensive 
refining. 

(5)  It  must  be  pure  mineral  oil  neutral  in  reaction. 

(6)  It  should  have  a  high  fire  test,  over  170°  C. 

(7)  It  should  be  resistant  to  oxidation,  i.e.  should  give 
a  good  "  sludging  test." 

This  "  sludging  "  is  one  of  the  main  troubles.  The  sludge 
always  contains  oxygen.  A  sludging  test  has  therefore  been 
designed  based  on  the  behaviour  of  the  oil  when  oxygen  is 
bubbled  through  it  for  several  hours  under  fixed  conditions. 

A  special  type  of  lubricating  oil  is  medicinal  oil.  This 
is  nothing  more  or  less  than  a  highly  refined  oil  of  moderate 
viscosity.  Various  specifications  for  this  product  have  been 
drawn  up  by  the  pharmacopoeia  of  various  countries.  The 


2So     PETROLEUM  AND  ALLIED  INDUSTRIES 

specific  gravity  usually  lies  between  0*870  and  0*920  at  15°  C. 
The  oil  must  be  colourless,  odourless,  and  tasteless,  have  no 
fluorescence,  be  neutral  in  reaction,  leave  no  ash  on  ignition, 
must  separate  no  paraffin  wax  at  o°  C.,  and  must  show  only 
a  slight  colour  after  shaking  for  five  minutes  with  twice  its 
volume  of  a  mixture  of  nitric  and  concentrated  sulphuric 
acids  in  the  proportions  of  three  to  one.  The  viscosity 
should  be  about  300  Saybolt  at  100°  F.  (16°  E.  at  20°  C., 
105  R.I  at  100°  F.). 


GENERAL   REFERENCES   TO   PART   VIIL,    SECTION   F. 

Archbutt  and  Deeley,  "  Lubrication  and  Lubricants."     C.  Griffin  and  Co. 
Battle,  "  Industrial  Oil  Engineering."     C.  Griffin  and  Co. 
Hurst,    "  Lubricating   Oils,    Fats,    and    Greases."     Scott,    Greenwood 
and  Co. 

Thomsen,  "  Practice  of  Lubrication."     McGraw  Hill  Book  Co. 


SECTION  G.— ASPHALTS 

IN  the  early  days  of  the  industry  the  crude  oils  first  worked 
in  America  were  of  the  paraffin  base  type.  Those  of  the 
European  and  Asiatic  fields  later  developed,  though  largely 
of  naphthene  base,  contained  relatively  little  asphalt, 
so  that  the  distillation  residues  were  liquid  and  suitable  for 
fuel.  Only  comparatively  recently  did  the  heavy  Mexican 
crudes  with  their  large  asphaltic  content  appear  on  the 
scene.  Strangely  the  ever-extending  use  of  light  petroleum 
tractions  for  motor  transport  has  brought  about  a  demand 
for  the  heaviest  constituents,  viz.  the  road  oils  and  asphalts. 
The  necessity  for  good  roads  which  can  stand  up  to  modern 
heavy  traffic,  and  the  superiority  of  petroleum  asphalts  for 
this  purpose  is  being  generally  recognized.  Moreover,  the 
general  tendency  of  the  coal  carbonizing  industry  towards 
vertical  and  even  low-temperature  retorts,  renders  the  coal 
tar  available  less  suitable  than  formerly  for  road-making 
purposes. 

By  far  the  most  important  application  of  the  asphalts 
is  in  connection  with  road  making  or  paving  in  one  form  or 
another.  The  application  of  the  naturally  occurring  asphalt- 
impregnated  rocks  for  road  surfacing  has  already  been 
described,  as  has  also  the  application  of  the  naturally  occurring 
asphalts  of  Trinidad  and  Venezuela,  together  with  the 
petroleum  residual  asphalts  for  the  same  purpose  (Part  V., 
Section  B). 

Some  idea  of  the  extent  to  which  asphalts  are  used  may 
be  gleaned  from  the  following  figures  :  The  total  consump- 
tion of  asphalt  of  all  kinds  in  the  United  States  for  1919  was 
1,443,289  tons.  About  86  per  cent,  of  this  was  manufactured 
from  petroleum ;  native  asphaltites  and  pyrobitumens 

281 


282     PETROLEUM  AND   ALLIED  INDUSTRIES 

were  responsible  for  2*3  per  cent.,  and  natural  asphalts  from 
Trinidad  and  Venezuela  for  67  per  cent.  (Hubbard,  Chemical 
Age,  New  York,  August,  1921).  It  is  estimated  that  the 
asphalt  used  in  the  United  States  for  road  construction  alone 
during  1921  amounted  to  634,000  tons.  The  present  annual 
consumption  of  asphalt  for  the  roofing  industry  in  the  United 
States  is  estimated  at  625,000  tons,  so  that  these  two 
outlets  alone  account  for  nearly  90  per  cent,  of  the  total 
consumption. 

Apart  from  road  construction,  asphalts  are  used  in 
connection  with  the  following :  impregnated  fabrics  for 
roofing,  flooring,  waterproofing  and  insulating  purposes, 
also  paints,  varnishes,  japans,  pipe-dipping  compounds, 
acid-resisting  compounds,  etc.,  etc. 

In  the  manufacture  of  "  roofing  felt "  two  distinct 
operations  are  necessary,  viz.  "  impregnation  "  and  "  sur- 
facing." For  impregnating,  a  material  of  penetration  not 
more  than  60  at  77°  F.  and  melting  point  from  100-160°  F. 
(ring  and  ball  method)  is  usually  employed.  Native  or 
prepared  asphalts,  also  products  such  as  wood-tar  pitch, 
rosin  pitch  or  fatty-acid  pitch,  may  be  used,  fluxed  if  necessary 
to  the  required  consistency  by  means  of  soft  asphalts  or 
flux  oils.  Such  impregnating  mixture  should  naturally 
have  a  flash-point  well  above  the  working  temperature  for 
impregnation,  which  may  be  as  high  as  200°  C.  It  should 
also  contain  a  large  percentage  soluble  in  0*645  petroleum 
ether  (malthenes).  For  surfacing  or  for  cementing  together 
several  layers  of  impregnated  fabric  into  a  composite  sheet, 
similar  mixtures,  but  of  a  somewhat  higher  melting  point 
and  consistency  are  used.  Such  mixtures  should  possess 
the  following  characters  :  penetration  from  10  to  50  at 
77°  F.,  melting  point  not  below  160°  F.  (ring  and  ball), 
low  volatility  and  high  flash-point  (as  above) .  The  weather- 
resisting  properties  are  apparently  improved  by  the  admix- 
ture of  fatty  substances,  also  of  opaque  material  such  as 
graphite  or  lampblack,  which  act  as  absorbers  of  the 
actinic  rays. 

The  action  of  "  weathering  "  on  asphalts  has  been  studied 


ASPHALTS  283 

by  Hubbard  and  Reeve  (J.  Ind.  and  Eng.  Chem.,  vol.  5,  p.  15) 
and  L,ewis  (7-  Ind.  and  Eng.  Chem.,  vol.  9,  p.  743).  They 
find  that  the  changes  consequent  on  weathering  are  due  to 
evaporation,  oxidation  to  form  oxidized  products,  elimina- 
tion of  hydrogen  by  oxidation,  and  polymerization.  Exposure 
to  weather  has  the  following  effects :  the  penetration, 
melting  point,  flash-point  and  fixed  carbon  content  all 
increase,  while  the  ductility,  adhesiveness,  solubility  in 
carbon  bisulphide  and  in  0-645  petroleum  spirit  all  diminish. 
This  is  in  agreement  with  the  gradual  change  known  as 
inspissation,  the  action  of  which  in  nature  is  inferred  from 
the  relations  of  the  natural  asphalts  to  the  asphaltites  and 
pyrobitumens. 

The  impregnated  fabrics  are  manufactured  simply  by 
running  the  material  through  a  bath  of  the  melted  impreg- 
nating material.  Roofing  felt  will  absorb  about  130  per  cent, 
by  weight  of  asphalt.  The  surface  of  the  finished  material, 
after  treating  with  the  surfacing  coat,  may  be  further 
coated  with  talc,  sand,  or  even  fine  pebbles -according  to 
taste.  For  a  full  description  of  the  method  of  manufacture 
of  roofing  felt,  asphalt  shingles  and  their  applications,  the 
reader  is  referred  to  Chap.  XXV.  of  Abrahams'  excellent 
book  on  "  Asphalts  and  Allied  Substances "  (D.  van 
Nostrand  Co.). 

Asphalt  saturated  felt  is  also  used  as  a  ' '  substitute  for 
linoleum,"  in  which  case  it  merely  acts  as  a  support  for  a 
layer  of  the  linoleum  composition  on  the  upper  surface. 
Impregnated  cotton  fabric  is  also  largely  used  for  "  damp- 
proof  courses  "  in  buildings.  "  Insulating  papers  "  are  also 
largely  made  by  impregnating  suitable  papers  with  asphalt 
mixtures  as  used  for  roofing  felt,  also  with  other  petroleum 
products,  such  as  paraffin  wax  and  cylinder  oils.  Such 
papers  are  used  for  insulating  refrigerator  vans,  ice  chests, 
etc.,  also  for  electrical  purposes.  Insulating  tape  is  made 
in  a  similar  way. 

Asphalt  enters  into  the  composition  of  "pipe-dipping 
mixtures,"  used  to  protect  iron  or  steel  piping  which  is  liable 
to  exposure  to  damp  soil  containing  corrosive  salts,  and  to 


284    PETROLEUM  AND  ALLIED  INDUSTRIES 

electric  currents.  The  dipping  mixture  used  must  be 
durable  and  tough  and  adhere  well  to  the  metal.  The  pipes 
to  be  dipped  are  heated  to  about  200°  C.,  and  then  immersed 
in  a  bath  of  the  asphalt  at  the  same  temperature.  On 
withdrawal,  they  are  heated  or  baked  before  cooling.  A 
number  of  "  bituminous  paints  and  varnishes  "  are  on  the 
market  and  are  used  for  a  variety  of  purposes,  such  as  water- 
proofing walls,  protecting  wood  and  metal  surfaces,  etc. 
Bituminous  paints  are  merely  solutions  of  asphalt  in  suitable 
solvents,  which  on  evaporation  leave  the  asphalt  distributed 
over  the  surface.  Bituminous  varnishes  contain  also  vege- 
table drying  oils  which  contribute  to  the  drying  and  harden- 
ing of  the  film,  as  in  the  case  of  ordinary  oil  paints.  The 
so-called  "  mineral  rubber,"  is  also  a  petroleum  product. 
The  best  grades  consist  of  mixtures  of  blown  asphalt  and 
gilsonite,  the  gilsonite  being  usually  mixed  with  the  asphalt 
before  the  blowing  operation.  These  mineral  rubbers  are 
used  for  incorporating  into  natural  rubber  with  which  they 
are  masticated.  C.  O.  North  (Chem.  and  Met.  Engineering, 
1922,  p.  253)  has  investigated  this  subject  and  has  found 
that  mineral  rubber  when  mixed  in  in  proportions  from 
3  to  15  per  cent,  has  a  beneficial  effect  on  the  properties 
of  the  rubber.  In  proportions  greater  than  15  per  cent., 
however,  it  affects  the  rate  of  recovery  of  the  rubber. 


GENERAL   REFERENCES   TO    PART   VIII.,    SECTION   G. 

Abrahams,  "  Asphalts  and  Allied  Substances."     D.  van  Nostrand  Co. 
Kohler  und  Graefe,  "  Natiirliche  und  Kiinstliche  Asphalte."     Vieweg 
und  Sohn,  Braunschweig. 


PART  IX.— THE  TESTING  OF  PETROLEUM 
PRODUCTS 

As  the  subject  of  the  testing  of  petroleum  products  is  fully 
dealt  with  in  numerous  books  and  publications,  the  descrip- 
tion of  detailed  methods  here  would  serve  no  useful  purpose. 
It  is  proposed,  therefore,  merely  to  present  a  few  general 
considerations  on  the  subject  together  with  a  few  data 
dealing  with  the  relation  of  several  of  the  instruments  in 
general  use  to  each  other. 

The  tests  applied  to  petroleum  products  fall  at  once 
into  two  categories,  (a)  those  which  are  applied  according  to 
the  methods  of  exact  chemical  analysis,  and  (b)  those  which 
are  applied  by  means  of  apparatus  of  specified  dimensions 
operated  in  a  specified  manner. 

Under  the  former  heading  fall  such  determinations  as 
elementary  organic  analysis,  percentage  of  sulphur,  the 
determination  of  certain  physical  constants,  solubilities, 
and  so  forth.  Under  the  latter  heading  fall  all  the  determina- 
tions of  the  values  of  such  properties  as  flash-point,  viscosity, 
distillation  range,  colour,  illuminating  power,  melting  point, 
penetration,  ductility,  and  the  like. 

The  fact  that  the  bulk  of  the  determinations  usually 
carried  out  are  of  such  an  empirical  nature  has  brought 
about  a  position  of  chaos  in  this  respect.  Co-operation 
between  large  firms  and  between  petroleum  organizations  in 
various  countries  has  been  practically  non-existent,  with  the 
result  that  there  are  almost  as  many  instruments  in  use  for 
testing  flash-points,  for  example,  as  there  are  countries.  Prior 
to  the  great  war  an  International  Petroleum  Congress  had 
been  formed,  one  of  the  aims  of  which  was  the  standardizing 

285 


286    PETROLEUM  AND  ALLIED  INDUSTRIES 

of  methods  of  testing,  but  this  organization  has  unfortunately 
become  defunct.  The  subject  has,  however,  recently  received 
the  attention  of  the  American  Society  for  Testing  Materials, 
a  society  which  has  already  done  much  work,  and  is  now 
also  receiving  the  attention  of  the  recently  formed  Standardi- 
zation Committee  of  the  Institution  of  Petroleum  Technolo- 
gists in  this  country.  If  these  two  bodies  work  together, 
a  much  desired  uniformity  in  testing  methods  may  be  brought 
about  (Brame,  Presidential  address  to  Inst.  of  Pet.  Tech., 
March,  1922).  Until  this  much-to-be-desired  state  of 
affairs  results,  a  few  words  dealing  with  the  subject  generally 
may  not  be  out  of  place. 

Of  the  determinations  which  fall  in  the  first  category 
mentioned  above  little  need  be  said.  The  usual  physical 
constants  can  be  determined  with  accuracy  by  the  usual 
methods.  Even  in  the  expression  of  such  a  simple  and 
important  constant  as  specific  gravity  there  is,  however, 
no  uniformity.  In  America  the  arbitrary  Beaume  scale  is 
used.  In  other  countries  there  is  often  much  confusion  as 
to  whether  the  specific  gravity  is  referred  to  water  at  15°  C., 
60°  F.,  or  4°  C.  This  may  lead  to  disputes  in  the  determina- 
tion of  the  weights  of  cargoes  of  oil.  Moreover,  the  figures 
used  as  coefficients  for  converting  the  specific  gravity  at  any 
temperature  t°  to  the  standard  temperature  of  reference 
are  neither  accurately  determined  nor  even  generally  agreed. 
The  elementary  chemical  analyses  may  be  made  in  the  usual 
way.  Sulphur  may  be  estimated  by  the  calorimeter  bomb, 
and  in  the  case  of  light  products,  such  as  benzines  and 
kerosenes,  may  be  accurately  estimated  by  one  of  the  methods 
based  on  burning  the  oil  in  a  current  of  air,  absorbing  the 
resulting  sulphur  dioxide  and  estimating  it  as  sulphate  or 
otherwise  (lyomax,  J.I.P.T.,  1917,  p.  19  ;  Bowman,  J.I.P.T., 
1921,  P-  334  ;  Esling,  J.I.P.T.,  1921,  p.  83). 

Methods  of  estimating  the  percentage  of  the  various 
chemical  compounds  or  even  classes  of  hydrocarbons  present 
in  a  crude  oil  or  even  in  a  light  distillate  are  by  no  means 
reliable  and  yield  only  approximate  results.  Olefines  may 
be  estimated  by  removal  by  sulphuric  acid,  by  bromine  or 


THE   TESTING  OF  PETROLEUM  PRODUCTS    287 

iodine  absorption,  or  by  reaction  with  potassium  permanga- 
nate, but  all  these  methods  give  unsatisfactory  results 
(Chavanne  and  Simon,  Comptes  rendus,  1919,  pp.  70,  in  ; 
Lomax,  J.I.P.T.,  1917,  p.  22  ;  Bowrey,  J.I.P.T.,  vol.  3, 
p.  287).  The  question  of  determining  the  percentage  of 
aromatic,  naphthene,  and  paraffin  hydrocarbons  in  a  motor 
spirit  is  one  of  importance.  Perhaps  the  best  and  simplest 
method  so  far  evolved  is  that  of  Tizard  and  Marshall  (J. S.C.I., 
vol.  40,  p.  20T)  (vide  also  p.  26).  While  this  method  gives 
reliable  values  for  the  aromatics,  the  values  indicated  for 
naphthenes  are  approximate  only.  In  the  case  of  products 
containing  compounds  of  high  molecular  weight,  methods 
are  even  less  satisfactory.  Asphalts  are  examined  according 
to  their  solubility  in  various  chemical  solvents,  and  the 
existence  of  bodies  termed  asphaltenes,  carbenes,  malthenes, 
etc. ,  is  thereby  inferred.  The  figures  so  obtained  are  doubtless 
of  some  value,  as  they  can  be  correlated  with  variations  in 
the  method  of  manufacture  and,  moreover,  give  useful 
indications  as  to  the  origin  of  the  product.  How  dependent 
these  values  are  on  conditions  is  well  exemplified  by  the 
work  of  Mackenzie  (/.  Ind.  and  Eng.  Chem.,  1910,  p.  124), 
who  showed  that  the  amount  of  carbenes  found  largely 
depends  on  the  exposure  to  light  during  the  estimation. 

When  methods  of  the  second  category  are  considered, 
very  great  diversity,  both  in  apparatus  and  methods  of 
testing,  are  at  once  obvious.  In  the  case  of  the  examination 
of  benzines  for  range  of  boiling  points  several  methods 
have  been  largely  used.  Among  these  may  be  mentioned  the 
Engler  and  the  Ubbelohde,  with  their  many  modifications. 
In  the  case  of  the  Engler  test,  the  flask  and  its  contents 
are  weighed,  and  after  distillation  to  a  definite  temperature, 
the  contents  are  again  weighed,  the  percentage  distilling  up 
to  that  temperature  being  determined  by  the  loss  of  weight. 
The  distillation  in  this  case  is  interrupted  at  the  temperature 
in  question,  and  after  the  flask  has  been  allowed  to  cool 
somewhat,  heat  is  again  applied  until  the  temperature  of 
the  vapour  again  reaches  the  point  in  question.  This  opera- 
tion is  repeated  several  times  (usually  three).  This  method 


288    PETROLEUM  AND  ALLIED  INDUSTRIES 


differs  fundamentally  therefore  from  the  Ubbelohde  method 
in  general  use  in  that  the  distillation  in  the  latter  case  is 
carried  on  continuously,  the  percentages  boiling  over  up  to 
any  definite  temperatures  being  expressed  in  volumes.  The 
Bngler  method  usually  yields  results  about  5  per  cent, 
higher  than  those  given  by  the  Ubbelohde  method,  in 
distilling  to  100°  C.  The  liability  to  personal  error  in  the 
Bngler  method  is  great,  moreover,  as  the  percentage  distilling 
over  is  determined  by  loss  of  weight  and  not  by  measuring 
the  distillate  collected,  the  very  volatile  gaseous  or  noncon- 
densable  fractions  which  would  otherwise  be  lost  are  included. 
Something  is,  of  course,  to  be  said  on  both  sides  of  this 
question.  I,omax  (J.I.P.T.,  1917,  p.  7)  gives  figures  com- 
paring the  Engler  and  Redwood  methods,  this  latter  method 
being  to  all  intents  and  purposes  identical  with  the  Ubbelohde 
method  (except  in  so  far  as  the  method  of  determining  the 
initial  boiling  point  is  concerned). 


Redwood.    Engler. 

Redwood.    Engler. 

Percentage  to  100°  C. 
to  125°  C  
to  150°  C  
Final  boiling  point 
Time  for  test  (minutes) 

5            II 

60            65 
89            90 
176          175 
5°           90 

8            16 
61            67 

9°           93 
176          174 
55           90 

A  form  of  apparatus  used  in  France,  not  only  for  benzine 
but  also  for  kerosene  and  fuel  oils,  is  the  IvUynes-Bordas.  It 
consists  of  a  copper  retort  of  special  design  enclosed  in  an 
iron  casing,  connected  to  a  metal  water-cooled  condenser. 
In  the  case  of  benzine  the  thermometer  is  immersed  in  the 
vapour,  but  when  distilling  kerosene  or  fuel  oils  it  is  placed 
in  the  liquid.  As  compared  with  the  Ubbelohde  test  for 
benzine  the  lower  fractions  distil  at  slightly  higher  tempera- 
tures and  the  higher  fractions  at  slightly  lower  temperatures. 
The  figures  given  below  illustrate  a  comparative  test  with 
the  two  types  of  apparatus  : — 


Luynes  Bordas 

Ubbelohde  at 

at  temperature  °C. 

temperature  °C. 

72-6 

67'3 

87-5 

84-8 

1047 

106*9 

IJ3 

115-2 

I58-3 

160*4 

175 

i75'5 

THE   TESTING  OF  PETROLEUM  PRODUCTS    289 

Volume  distilled 
over  (per  cent.). 

5 

20 

45 

55 

90 

95 

The  apparatus  is  very  sensitive  to  changes  in  the  rate  of 
distillation.  With  kerosene  the  distillation  results  of  the 
two  methods  show  greater  divergence.  The  method  of 
Ubbelohde  as  modified  by  the  American  Society  of  Testing 
Materials  (E.  W.  Dean,  Bureau  of  Mines,  Technical  Paper  166), 
may  be  recommended  for  general  adoption. 

The  determination  of  the  flash-point  of  kerosenes  is  a 
subject  which  has  received  much  attention.  In  the  British 
Empire  the  Abel  method  is  the  standard,  on  the  Continent 
the  Abel-Pensky  modification  is  used,  the  personal  factor 
of  the  Abel  apparatus  being  eliminated  by  the  use  of  a  dock- 
work  device.  In  the  United  States  several  flash-point 
testers  are  in  use  such  as  the  Tagliabue  closed  cup,  the  Foster 
and  the  Elliot.  Allen  and  Crossfield  have  recommended 
a  modified  Abel-Pensky  apparatus  (Bureau  of  Mines, 
Technical  Paper  49) .  Taking  the  Abel-Pensky  as  a  standard, 
the  Tagliabue  closed  cup  gives  results  3°  C.  higher ;  the 
Foster  6°  C.  higher,  and  the  Elliot  5°  C.  lower.  The 
German  type  of  Abel-Pensky  gives  results  37°  F.  higher 
than  the; Abel.  In  France  the  Luchaire  type  of  flash-point 
tester  is  in  general  use. 

For  the  testing  of  colour  many  forms  of  instruments 
are  in  use.  They  may  be  divided  roughly  into  two  classes, 
(a)  those  which  match  the  tint  of  a  definite  thickness  of  oil 
with  various  standardized  coloured  glasses,  (b)  those  which 
match  the  tint  of  a  standard  coloured  glass  by  varying 
the  thickness  of  the  layer  of  oil  looked  through.  To  the 
former  class  belong  the  instruments  of  I^ovibond  and  Wilson, 
to  the  latter  those  of  Say  bolt  and  Stammer.  For  detailed 
descriptions  of  these  instruments  the  reader  may  be  referred 
p.  19 


2(jo    PETROLEUM  AND   ALLIED  INDUSTRIES 

to  Campbell's  "  Petroleum  Refining  for  lyovibond,"  Kansas 
City  Testing  laboratory,  Bulletin  14  for  Saybolt,  and  to 
Holde,  "  Die  Untersuchung  der  Mineralole  und  Fette," 
for  Stammer.  The  L,ovibond  instrument  is  also  supplied 
with  a  fine  range  of  glasses  of  yellow  and  red  tints,  in  addition 
to  the  standard  glasses  for  kerosene ;  the  Stammer  has  the 
advantage  that  the  thickness  of  the  column  of  liquid  under 
observation  may  be  varied  either  way  as  often  as  required. 

The  trade  terms  used  to  designate  the  colours  of  kerosenes 
are  Water- white,  Superfine- white,  Prime- white  and  Standard- 
white.  These  terms  have  unfortunately  not  precisely 
equivalent  values  on  different  instruments. 

Fig.  44  shows  at  a  glance  the  comparative  readings  of 


WW300J 

w 

vy. 

250   " 

w. 

W.W 

1 

- 

20_ 

Sw.W.200_I 

1-5 

150^ 

- 

S<4, 

Vy     s*-w- 

-2 

looj 

- 

_3 

PW.  -" 

'°-7 

5, 

vv. 

« 

Sd.W.50_I 

54 

_5 

. 

°_E 

Sd.W. 

PW. 

6 

- 

5.1 

S«L 

w 

_7 

- 

IO_S 

SdirV. 

~  8 

o__ 

FIG.  44. — Comparative  colorimeter  readings,  using  benzine  and 
kerosene. 


the  four  types  of  instrument  mentioned.  Francis  (Nat*  Pel. 
News,  June  10, 1921,  p.  34)  gives  a  useful  comparison  between 
the  Saybolt  and  I^ovibond  instruments,  and  compares  this 
latter  type  also  with  the  Union  Petroleum  Colour  Standards 


THE   TESTING   OF  PETROLEUM  PRODUCTS     291 

and  colorimeter  used  in  the  United  States  for  the  testing 
of  lubricating  oils. 

There  are  also  numerous  types  of  instruments  in  use 
for  determining  the  flash-points  of  heavy  oils,  fuels,  lubri- 
cating oils  and  so  forth.  The  order  of  accuracy  of  these 
instruments  is  not  so  great  as  those  used  for  flash-points 
at  lower  temperatures,  but  the  need  for  accuracy  is  not  so 
great.  The  type  in  most  general  use  is  the  Pensky  Marten  ; 
the  Cleveland  open  cup  and  the  Gray  tester  are  in  use  in 
the  United  States. 

The  influence  of  water  on  the  flash-point  must  be  noted, 
as  unless  the  oils  to  be  tested  are  dry,  errors  of  as  much  as 
20°  F.  in  the  flash-point  may  be  made,  the  wet  oil  giving  the 
higher  value.  The  presence  of  i  per  cent,  of  water  usually 
renders  the  determination  impossible.  Even  with  dry  oils, 
successive  determinations  by  the  same  observer  may  differ 
by  as  much  as  7°  or  8°  F. 

A  large  number  of  instruments  have  been  designed  for 
the  testing  of  viscosity.  Owing  to  thegreat  range  of  viscosities 
to  be  determined,  varying  from  that  of  a  light  spindle  oil 
to  that  of  a  heavy  cylinder,  thick  fuel  or  flux  oil,  one 
instrument  of  any  type  cannot  well  cover  the  whole  range. 
For  the  more  viscous  oils,  therefore,  special  types  have  been 
designed.  There  is,  however,  great  lack  of  co-operation  in 
this  matter  ;  not  only  do  the  instruments  in  use  in  different 
countries  differ,  but  even  the  mode  of  expressing  the  results 
obtained. 

The  absolute  viscosity  of  an  oil  is  "  the  force  which  is 
required  to  move  a  unit  area  of  plane  surface  with  unit 
velocity  relative  to  another  parallel  plane  surface  from  which 
it  is  separated  by  a  layer  of  the  oil  of  unit  thickness  " 
(Herschel,  U.S.A.  Bureau  of  Standards,  Technologic  Paper, 
No.  100).  The  unit  of  absolute  viscosity  is  termed  the 
"  poise." 


F  being  the  force  in  dynes  required  to  slide  two  parallel 
plates,  each  of  area  a  square  centimetres,  over  one  another 


292     PETROLEUM  AND   ALLIED  INDUSTRIES 

at  a  velocity  of  v  centimetres  per  second,  when  separated 
by  a  layer  of  oil  of  absolute  viscosity  p  and  thickness  a 
centimetres. 

The  absolute  viscosity  of  water  at  20°  C.  is  0*01005  poises. 
Specific  viscosity  is  the  ratio  between  the  absolute  viscosity 
of  the  substance  and  that  of  the  absolute  viscosity  of 
water  at  the  same  temperature.  In  practice,  however,  the 
absolute  viscosity  of  water  at  20°  C.  is  taken  as  the  reference 
figure. 

The  absolute  viscosity  of  an  oil  is  determined  in  practice 
by  the  capillary  tube  method  (Archbutt  and  Deely,  "  Lubri- 
cation and  lyubricants,"  p.  155).  For  commercial  use, 
however,  relative  viscosities  only  are  usually  required  and 
these  are  determined  by  a  number  of  different  instruments, 
most  of  which  depend  upon  the  measurement  of  the  time  of 
flow  of  a  definite  volume  of  the  liquid  through  an  orifice  of 
definite  dimensions  under  definite  conditions  of  temperature 
and  head.  The  instruments  in  most  general  use  are  the 
Engler  on  the  Continent,  the  Redwood  in  England,  and  the 
Saybolt  in  the  United  States.  For  very  viscous  oils  a  special 
Redwood  Admiralty  type,  usually  known  as  Redwood  II. 
possessing  a  much  larger  orifice  is  in  use  in  England,  and  a 
Saybolt  Furol  instrument  in  the  United  States.  Descrip- 
tions of  these  instruments  are  given  in  most  of  the  books 
dealing  with  the  testing  of  petroleum  products,  e.g.  Battle, 
"  Industrial  Oil  Engineering,"  Griffin  and  Co.  These  instru- 
ments give  values  which  are  approximately  proportional 
to  actual  viscosities  particularly  when  oils  of  high  viscosity 
are  examined.  When  mobile  liquids  are  examined  the  rate 
of  flow  depends  by  no  means  entirely  on  the  viscosity,  as 
it  is  influenced  by  the  necessary  increase  in  kinetic  energy 
of  the  liquid,  while  flowing  through  the  nozzle,  which 
naturally  impedes  the  flow.  This  kinetic  effect,  how- 
ever, becomes  negligible  when  the  viscosity  of  the  liquid 
exeeds  about  10°  Engler  at  the  testing  temperature.  As 
a  consequence  of  this  kinetic  effect,  conversion  factors 
for  translating  the  reading  of  one  type  of  commercial 
viscosimeter  into  the  equivalent  reading  of  another  type 


THE    TESTING  OF  PETROLEUM  PRODUCTS     293 

are  not  constant,  but  vary  somewhat  with  the  viscosity  of 
the  oil. 

With  this  reservation  a  table  can  be  drawn  up  giving  the 
relative  values  of  viscosities  as  determined  by  the  various 
instruments,  at  the  same  temperature.  In  order  to  calculate 
the  viscosity  of  an  oil  on  another  instrument  at  a  different 
temperature,  a  knowledge  of  the  viscosity  curve  showing 
the  relation  of  viscosity  to  temperature  for  that  particular 
oil  would  be  necessary. 

The  following  figures  may  be  taken,  therefore,  only  as  a 
rough  guide  : — 

Engler  seconds.  Redwood  I.  seconds.  Saybolt  seconds. 

56  21'5  32H 

66  34-6  39-3 

75  39'8  45'5 

85  457  52-5 

100  54-3  63-0 

130  7i7                             83-5 

160  89*1  !04'4 

200  111*9  131*6 

250  140-3  165-5 

300  168-5  J98'8 

350  197-0  233-2 

400  225-5  266-5 

500  282*0  334-0 

600  339*0  400 'o 

The  factors  for  converting  Saybolt  to  Engler  will  thus  be  seen 
to  vary  from  1*73  for  an  oil  of  about  i°  Engler  to  1*50  for  an 
oil  of  about  10°  Engler  (i°  Engler  equals  approximately 
53  seconds,  but  varies  somewhat  with  different  instru- 
ments). 

As  approximate  values  the  conversion  factors  for 
Redwood  I.  to  Redwood  II.  may  be  taken  as  0*091  and  for 
Saybolt  to  Saybolt  Furol  as  1*05  (Herschel,  loc.  cit.).  The 
readings  of  the  commercial  instruments  can  be  converted 
into  absolute  viscosities  by  the  formulae  given  by  Herschel 
(U.S.  Bureau  of  Standards,  Circular  No.  112). 


294    PETROLEUM  AND   ALLIED  INDUSTRIES 
Absolute  viscosity 

=  Sp.gr.(  0-00213  Saybdt     - 

=  Sp.  gr.  (  0-00147  Engler 


=  Sp.  gr.  (  0-00260  Redwood  —  _    ,        ,  T  ) 
V  Redwood  I.  / 

The  calculation  of  the  viscosities  of  mixtures  of  oils  is 
almost  impossible  unless  the  two  oils  used  are  of  viscosities 
very  slightly  different,  a  case  seldom  met  with  in  practice. 
Viscosity  numbers  are  not  additive  figures.  The  influence 
of  the  lower  viscosity  oil  is  always  much  greater  than  would 
be  expected.  This  subject  has  been  investigated  by  Dunstan 
and  Thole  ("  The  Viscosity  of  liquids/'  p.  39),  Espy 
("  Petroleum,"  1919,  p.  27),  Herschel  (Bureau  of  Standards, 
Tech.  Paper  112),  and  others.  A  summary  of  their  work 
may  be  found  in  Hamor  and  Padgett,  "  The  Examination 
of  Petroleum,"  p.  357. 

The  tests  usually  applied  to  the  heavy  asphaltic  products 
of  petroleum  are  largely  of  an  even  more  empirical  nature 
than  those  above  described.  Two  types  of  penetrometers 
are  in  use,  that  of  Dow  and  that  of  the  New  York  Testing 
laboratory,  but  both  operate  on  the  same  principle,  and  give 
practically  the  same  results  under  similar  conditions. 

Several  methods  are  in  use  for  the  determination  of  the 
melting  point  of  asphalts.  As  such  substances  gradually 
soften  and  have  no  definite  melting  point  any  test  must  be 
quite  empirical.  A  comparison  of  the  chief  methods  is 
given  in  Chem.  and  Met.  Engineering,  1919,  p.  81.  The 
ring  and  ball  method  gives  consistent  readings,  but  the 
personal  error  may  be  large.  The  Kramer  and  Sarnow 
method  gives  less  consistent  results  and  is  complicated  in 
operation.  This  test  gives  results  from  15°  to  25°  F.  lower 
than  those  given  by  the  ring  and  ball  method. 

The  total  bitumen  is  given  by  the  solubility  in  carbon 
bisulphide.  Any  organic  matter  insoluble  in  carbon 


THE   TESTING   OF  PETROLEUM  PRODUCTS    295 

bisulphide  is  often  erroneously  termed  free  carbon.  It  may 
be  free  carbon  in  some  cases,  but  it  must  be  remembered 
that  the  kerotenes,  the  chief  components  of  asphaltic  pyro- 
bitumens,  are  insoluble  in  carbon  bisulphide.  The  amount 
insoluble  in  petroleum  ether  (sp.  gr.  0*645)  is  usually  deter- 
mined, those  constituents  which  are  soluble  in  this  solvent 
being  termed  malthenes.  As  the  solvent  powers  of  petroleum 
ethers  depend  on  their  chemical  composition  (aromatics 
and  naphthenes  being  better  solvents  than  paraffins),  it 
is  as  well  to  use  only  petroleum  ether  composed  entirely 
of  paraffins.  The  constituents  which  are  insoluble  in 
petroleum  ether  are  often  termed  asphaltenes,  but  it  is  better 
to  restrict  this  term  to  the  constituents  insoluble  in  alcohol 
or  alcohol-ether  mixture.  The  constituents  of  some  asphalt- 
ites  which  are  soluble  in  carbon  bisulphide,  but  insoluble 
in  carbon  tetrachloride  are  termed  carbenes.  Carbenes 
are  not  found  in  petroleum  asphalts  unless  they  have  been 
overheated  during  manufacture.  The  presence  of  more 
than  0*5  per  cent,  of  carbenes  should  be  regarded  with 
suspicion. 

Several  methods  are  used  for  the  determination  of  the 
melting  point  of  paraffin  wax.  Although  this  is  quite  a 
definite  point  as  compared  with  the  melting  point  of  an 
asphalt,  the  various  methods  give  considerably  divergent 
results.  The  British  method  and  the  continental  method 
(ShukofT)  are  similar  in  principle.  A  thermometer  is  immersed 
in  a  quantity  of  the  melted  wax  and  the  cooling  curve  is 
drawn.  At  the  point  of  crystallization  the  latent  heat  evolved 
by  the  crystallizing  wax  causes  a  break  in  the  curve,  so  that 
the  thermometer  remains  stationary  for  a  short  time.  The 
temperature  at  which  this  occurs  is  taken  as  the  setting 
point.  The  American  method  is  more  empirical.  A 
thermometer  of  standard  dimensions  is  placed  with  three- 
quarters  of  its  bulb  immersed  in  melted  wax  contained 
in  a  bowl  3!  inches  diameter.  The  temperature  is  noted  when 
a  film  of  solid  wax  extends  from  the  sides  of  the  bowl  to  the 
thermometer.  The  American  method  gives  results  3°  F. 
above  those  given  by  the  British  method. 


296     PETROLEUM  AND  ALLIED   INDUSTRIES 

Numerous  other  tests,  some  of  value,  many  of  little  or 
no  value,  are  employed.  For  details  of  these  the  reader 
must  be  referred  to  one  of  the  many  books  dealing  specially 
with  this  subject. 


GENERAL  REFERENCES  TO  PART  IX. 

Hamor  and  Padgett,  "  The  Technical  Examination  of  Crude  Petroleum, 
Petroleum  Products,  and  Natural  Gas." 

Rittman  and  Dean,  "The  Analytical  Distillation  of  Petroleum." 
Bulletin  125,  U.S.  Bureau  of  Mines. 

Hubbard,  "  Laboratory  Manual  of  Bituminous  Materials."  Wiley  and 
Sons,  New  York. 

Holde,  "  Untersuchung  der  Mineralole  und  Fette."    J.  Springer,  Berlin. 

Graefe,  "  Laboratoriumsbuch  fur  die  Braunkohlenteer  -  Industrie." 
W.  Knapp,  Halle. 


SUBJECT   INDEX 


ABSORPTION  process  for  gasoline,  53 
Acid  sludge,  regeneration  of,  238 
Acid,  sulphuric,  action  of,  on  petro- 
leum, 201 
Agitators,  198 

Airlift  system  for  raising  oil,  81 
Albertite,  138 
Alcohol,  27,  216,  248 
Aniline  point  method  for  aromatics, 

26,  287 
Anticline,  34 

Aromatic    hydrocarbons   in    petro- 
leum, 22,  287 

as  motor  fuels,  244,  248 

in  tars,  126 
Asphalt,  131 

applications  of,  142,  281 

Bermudez,  132,  143 

macadam,  145 

manufacture  of,  173,  224 

rock,  134,  142,  281 

Trinidad,  132,  142,  281 
Asphaltic  pyrobitumens,  2,  131 

pyrobituminous  shales,  139 
Asphaltites,  i,  131,  135 

BACTERIA,  action  of,  on  petroleum, 
19,4o 

Baling  method  of  raising  oil,  73 

Bauxite,  202,  214 

Benzene.     Vide     aromatic     hydro- 
carbons 

Benzines,  applications  of,  241 
characters  of,  250 
manufacture  of,  159,  190 

Bitumen,  2,  130 

Blown  asphalts,  227 

Burton  process,  233 

CANDLES,  152,  269 
Carbon  black,  49 
Carbonization  of  coal,  125 

lubricating  oils,  277 
Casing  for  wells,  74 
Casinghead  gas,  47 

gasoline,  51 
Cementing,  75 


Centrifugal  method  for  dehydrating 

oils,  94 
Ceresin,  150 

Charcoal  absorption  process,  58 
Chemical  treatment  of  oils,  196 
Chemistry  of  petroleum,  15,  123, 

126,  273 
Coal,  relation  of,  to  petroleum,  27 

carbonization  of,  125 
Coke,  129 
Coking  test,  277 
Colorimeters,  289 
Compressed  asphalt  paving,  145 
Compression  process  for  gasoline,  52 
Condensers,  157 
Continuous  distillation,  163 
Core  drilling,  69 
Cracking  processes,  229 
Crude  oils,  2,  29,  61,  68,  155 
Cutting  oils,  221 
Cylinder  oils,  172,  217,  278 

DECOLORIZING  powders,  202,  239 
Dehydrating  of  crude  oil,  93 
Dephlegmators,  160,  178 
Derricks,  types  of,  70 
Desulphurizing  oils,  123,  200 
Detonation,  248 
Distillate  preheaters,  166 
Distillation,  continuous,  163 

of  crude  oil,  153 

of  light  oils,  1 88 

periodic,  155 

plant,  efficiency  of,  184 

steam,  173,  179,  189 

under  vacuum,  170 
Drilling  methods,  69 

EDELEANU  process,  16,  205 
Elaterite,  137 

Electric  dehydrating  plant,  95 
Emulsions,  94,  219 
Evaporation,  losses  by,  84,  88 

FATTY  acids,  28,  272 
Faults  in  oil-fields,  36 
Filter  pressing,  210 


297 


298 


SUBJECT  INDEX 


Fires  on  oil-fields,  83 

Fishing  operations,  79 

Flash-points,  289 

Flowing  wells,  -80 

Fractionating  columns,  190 

Fuel  oils,  applications  of,  265 
characters  of,  262 
manufacture  of,  1 74,  224 

GAS.     Vide  Natural  gas 
Gas  oils,  applications  of,  258 
manufacture  of,  159,  225 
Gilsonite,  135,  146 
Glance  pitch,  136 
Grahamite,  137,  146 
Greases,  222 
Grouting,  145 
Gushers,  80 

HALL'S  cracking  process,  234 
Heckmann  column,  191 
Helium,  30,  58 
History  of  petroleum,  6 
Hydrogenation  methods,  235 

IMPSONITE,  139 
Inspissation,  101 

Internal    combustion    engine,    effi- 
ciency of,  246 

KAPAK,  146 
Kerogen,  98,  121 
Kerosene,  159,  252 

LIGNITE,  127 

Lubricating  oils,  applications  of,  271 

chemistry  of,  273 

manufacture  of,  208 

MANJAK,  136 
Medicinal  oils,  221,  279 
Montan  wax,  101,  127,  150 
Motor  spirits,  characters  of,  241 
Mud  volcanoes,  43 

NAPHTHENES,  22,  248 
Natural  gas,  casinghead,  47 

composition  of,  49 

fields,  44 

production  of,  43 
Neutral  oils,  218 

OIL  shales,  characters  of,  97 

mining  of,  106 

retorting  of,  1 1 1 

testing  of,  108 
Ozokerite,  3,  20,  148 


PARAFFIN  WAX,  manufacture  of,  208 

applications  of,  268 
Paraffins,  3,  19,  121,  126 
Peat,  128 

Penetrometer,  144,  226 
Percussion  methods  of  drilling,  70 
Petrolatum,  221 
Petroleum,  chemistry  of,  15 

geology  of,  31 

history  of,  6 

jelly,  221 

origin  of,  38 

production  of,  9 
Pipelines,  89 
Porosity  of  oil  rock,  33 
Pumping  oil  wells,  81 
Pyrobituminous  shales,  100,  139 
Pyropissite,  128,  151 

REDISTILLATION  of  light  fractions, 

188 

Refrigerating  plant,  209 
Retorts  for  shale  distillation,   115, 

228 

Ring  packings,  193 
Rittmann  process,  234 
Rock  asphalt,  134,  142 
Rod  wax,  221 
Rotary  system  of  drilling,  77 

SALINE  domes,  35 
Sand  pump,  73 
Shales,  characters  of,  97 

mining  of,  107 

retorting  of ,  no 

testing  of,  108 
Sharpies  process,  Q.J. 
Shooting  wells,  82 
Sludge  acid,  238 
Spudding,  73 

Steam  refined  cylinder  oils,  217,  275 
Stills  for  crude  oil,  155 

tubular  for  crude  oil,  173 
Storage  of  oil,  85 
Sulphur  in  petroleum,  24,  197 
Sulphuric  acid,  action  of,  195,  201 
Swabbing,  82 
Sweating  process,  212 

TANKS,  86 

Tank  steamers,  90 

Tar,  4,  125 

Terpenes  in  petroleum,  24 

Testing  of  products,  285 

Topping  plants,  180 

Torbanite,  99,  103 

Transformer  oils,  279 

Tubular  stills,  175 

Turbine  oils,  279 


SUBJECT  INDEX 


299 


VACUUM  distillation,  170 
Viscosity,  291 
Vulcanized  asphalts,  227 

WASTE  on  oil-fields,  43,  83 
Waste  products,  utilization  of,  237 
Water,  flush  system,  77 


Water  gas  plant,  260 

shutting  off.  75 
Wax.     Vide  Paraffin  wax 
Wax  tailings,  4, 159 
White  spirit,  242 
Wild  catting,  36 
WOrtzilite,  138,  146 


NAME   INDEX 


AlSINMANN,  273 

Alabama,  61 

Alamo,  63 

Alberta,  24,  44,  64,  135 

Albrecht,  16 

Algeria,  25,  133 

Allen,  289 

Alsace,  60,  65,  82 

Amend,  201 

Anderson,  58 

Appalachian,  32,  45,  61,  217,  274 

Apscheron,  10 

Arabia,  133 

Archbutt,  273 

Argentine,  64,  133 

Assam,  65 

Athabasca,  33,  64,  135 

Australia,  136 

Austria,  104,  133 

Autun,  104 

BAICOI,  65 

Bailey,  109 

Baker,  89 

Baku,  10,  32,  273 

Balachani,  64 

Barbados,  136 

Barringer,  92 

Baskerville,  238 

Batoum,  89 

Beeby  Thompson,  33,  44,  83,  266 

Beilby,  114,  117 

Bermudez,  32,  131,  132,  134,  143, 

144 

Berthelot,  38 
Bibi  Eibat,  64 
Bohemia,  150 
Bolivia,  64 

Borneo,  19,  22,  60,  66,  215 
Botkin,  120 
Bowman,  286 


Bowrey,  18,  287 

Brame,  286 

Bransky,  16 

Brazil,  64,  105 

Breitenlohner,  229 

Briant,  39 

Brooks,  201 

Broxiere  les  Mines,  104 

Brunck,  n 

Bryson,  115 

Bulgaria,  104 

Burmah,  7,  10,  29,  32,  35,  43,  65, 

66,  169,  215,  268 
Burney,  118 
Burrell,  58 
Burton,  233 
Bury,  27,  237 
Bustenari,  65 
Byerley,  226 

CADELL,  103 

Cady,  58 

Caldwell,  107 

California,   19,  22,  25,  32,  44,  47, 

48,  63,  69,  80,  101,  105,  131,  133, 

141,  173,  218,  225 
Campina,  65 
Canada,  17,  21,  25,  47,  64,  85,  104, 

133,  200 
Carves,  n 
Caspian  Sea,  7,  43 
Castleton,  137 
Caucasus,  21,  22,  25,  64 
[  Chantour9ois,  38 
|  Charitschkoff,  16 
Chavanne,  26,  287 
Cheleken,  148 
Chercheffsky,  239 
Cherry,  236 
China,  7,  105 
Coast,  233 


300 


NAME  INDEX 


Coates,  24 

Colin,  201 

Colorado,  62,  98,  105,  106,  137 

Columbia,  64,  136 

Conacher,  101 

Conradson,  258,  277 

Constanza,  89 

Cottrell,  95,  141 

Crichton,  117 

Crossfield,  289 

Cuba,  8,  131,  133,  134,  137,  139 

Cunningham  Craig,  39,  41,  99,  101 

DALLE  Y,  187 

Darmois,  17 

Daubree,  38 

Day,  1 6,  235 

Dean,  61,  289 

De  Chambrier,  83 

Deely,  273 

De  La  Haye,  8 

Del  Monte,  118 

Derbyshire,  8,  65 

Dewar,  230 

Dexter,  47 

Divine,  238 

Dorset,  104 

Drake,  9 

Dunod,  239 

Dunstan,  201,  274,  294 

Dykema,  243 

EAST  INDIES,  10,  32,  35,  65,  66,  268 

Ebano,  63 

Edeleanu,  205 

Egloff,  236 

Egypt,  6,  10,  22,  32,  66,  136 

Ellis,  28,  236 

Ells,  64,  104 

Endle,  231 

Engler,  16,  24,  39,  101 

Esling,  286 

Espy,  294 

Esthonia,  104 

FISCHER,  27,  28,  41 

Forbes-Leslie,  103 

France,  8,  65,   104,  131,  133,  134, 

288 

Francis,  290 
Franks,  116 
Frasch,  200,  201 
Freeman,  118 
Friedel,  236 
Fyfe,  117 

GALICIA,  10,  19,  21,  22,  32,  65,  69, 

85,  148,  215,  268 
Garner,  277 


Gavin,  98,  109 
Germany,  133,  216 
Gessner,  8 
Gilpin,  1 6 
Glazebrook,  90 
Gluud,  27,  41 
Goodwin,  193 
Gossage,  187 
Graefe,  16 
Grand  Valley,  106 
Greece,  65,  131,  133 
Greenstreet,  235 
Grosby,  64 
Gulf,  62 

HACKFORD,  4,  27,  29,  41,  100,  101 

Hall,  201,  202,  205,  234 

Hancock,  8 

Hanport,  n 

Hardstoft,  32,  65 

Harries,  21 

Henderson,  117,  210 

Herold,  231 

Herschel,  291,  293,  294 

Higgins,  90,  148 

Hill,  109 

Hinckley,  58 

Holde,  272 

Hubbard,  134,  141,  282 

Humbolt,  38 

Humphrey,  201 

Hunt,  39 

ILLINOIS,  32,  62 
Indiana,  32,  62,  133 
Italy,  65,  104,  133 

ACCARD,  39 
ackfork  Valley,  137 
apan,  7,  25,  65,  66,  133 
ava,  66,  268 
ones,  22,  1 02 

KANSAS,  44,  47,  48,  58,  62,  105 

Kentucky,  50,  61,  105,  131,  133 

Kewley,  15 

Kimmeridge,  32,  104,  123 

Knab,  n 

Knibbs,  187 

Koetei,  66 

Kraemer,  24 

Krieble,  15,  24,  64,  135 

Kubierschky,  194 

LANGMUIR,  272 
Laurent,  8 
Leather,  23 
Lessing,  15,  193,  194 
Lewis,  283 


NAME  INDEX 


301 


Lima,  62 

Limmer,  33,  134,  135 

Loffl,  28 

Lomax,  no,  286,  287,  288 

Lothians,  103 

Louisiana,  35,  44,  50,  62,  133 

Luynes-Bordas,  288 

Lyder,  103,  in,  114 

MABERY,  20,  24,  41,  221,  273,  274 

Mackenzie,  287 

Maclaurin,  118 

Maikop,  65 

Mansfield,  104 

Maracaibo,  131,  132 

Marcusson,  24,  151,  273 

Markownikoff,  24,  239 

Marshall,  26,  287 

Matthews,  274 

McAffee,  236 

McFarland,  58 

McKee,  103,  in,  114 

McLennan,  58 

Meigs,  256 

Mendelejeff,  38 

Meserve,  58 

Mesopotamia,  6,  32,  66,  133,  139 

Mexico,  10,  19,  32,  35,  41,  63,  68, 
80,  101,  131,  133,  136,  139,  144, 
169,  173,  200,  224,  225,  268 

Midcontinent,  32,  35,  44,  62,  169, 
218 

Missouri,  133 

Moldavia,  148 

Montana,  50,  62,  105 

Moore,  236,  264 

Murdoch,  8 

NARANJOS  Los,  63 

Neal,  50 

Nevada,  105 

New  Brunswick,  8,  101,  103,  104, 

138 

Newfoundland,  105 
New  Mexico,  62,  105 
New  South  Wales,  105,  107,  216 
New  York,  48,  61 
New  Zealand,  67,  105 
Nielsen,  118 

Norfolk,  32,  103,  104,  1 06 
North,  284 

Nova  Scotia,  103,  105 
Nova  Zembla,  101 

OBERFELL,  58 

Ohio,  32,  44,  48,  61,  62,  101,  200 
Oil  Springs,  64 

Oklahoma,  48,  62,  105,  133,  137, 
139,  146 


Ollander,  27 
Ontario,  32,  44,  64,  69 
Orton,  39 

PADGETT,  231 

Palestine,  136 

Pannell,  90 

Panuco,  63 

Papua,  67 

Paris,  239 

Parish,  240,  271 

Pechelbronn,  65,  82 

Peckham,  25 

Pennsylvania,  8,  32,  44,  47,  48,  61, 

169,  170,  172,  208,  218,  273 
Perdew,  109 
Perrot,  51 

Persia,  6,  10,  19,  25,  33.  65,  66 
Peter,  18 
Petrolia,  64,  8 1 
Peru,  22,  64 
Pfaff,  152 

Philippines,  131,  133 
Pinat,  239 
Poelsch,  77 
Portlock,  8 
Portugal,  63,  133 
Potrero,  63 
Preston,  90 
Prym,  193 
Pschorr,  152 
Pumpherston,  115 
Pye,  247 

RAGUSA,  134,  135 

Raschig,  193 

Redwood,  230,  288 

Reeve,  283 

Reichenbach,  von,  8 

Remfrey,  no 

Ricardo,  20,  246,  247,  248 

Richards,  230 

Richardson,  141 

Riebeck,  9 

Rittman,  234 

Riviera,  104 

Robertson,  236 

Rocky  Mountains,  62 

Rolle,  128 

Romany,  64 

Ross,  23 

Rozet,  38 

Rumania,  10,  19,  21,  22,  35,  65,  82, 

Rozet,  38 

89,  148,  206,  268 
Russia,  10,  17,  32,  33,  35,  64,  68, 

74,  80,  82,  133,  169,  218 

SABATIER,  235 


302 


NAME   INDEX 


Saboontje,  64 
Sakhalin,  133 
Sarawak,  66 
Saxony,  10,  127 
Schaarschmidt,  28 
Schneider,  28 
Scotland,  9,  103,  114,  216 
Senderens,  235 
Seyer,  15,  24,  64,  135 
Seyssel,  134,  135 
Sharp-Hughes,  79 
Sharpies,  94 

Siberia,  65,  131,  133,  137 
Sicily,  133,  134 
Simon,  26,  287 
Simpson,  117,  119 
South  Australia,  137 
Southcombe,  272 
Spain,  65,  104,  133 
Spilker,  24 
Spindle  Top,  77 
Standinger,  231 
Steinschneider,  170 
Stewart,  117,  122 
Stirling,  81 
Storer,  39 
Sumatra,  19,  66 
Surachany,  64 
Sweden,  104 
Switzerland,  133,  134 
Syria,  131,  133 

TABASCO,  63 

Taranaki,  67 

Tasmania,  105,  139 

Tausz,  1 8,  21,  27 

Tehuantepec,  63 

Tennessee,  61 

Texas,  32,  35,  44,  48,  62, 

105,  133,  173,  218,  225 
Thiele,  28 
Thiessen,  51 
Thole,  274,  294 
Thorpe,  230 
Thuringia,  150 
Titusville,  9 
Tizard,  26,  247,  287 
Topila,  63 


77.  79, 


Torbane  Hill,  8,  103 

Transvaal,  105 

Trevor,  105 

Trinidad,  8,  32,  63,  133,  134,  137, 

143,  144,  225,  281,  282 
Trumble,  175 
Turkey,  104 
Tzintea,  65 

UBBELOHDE,  287 

Uinta,  135 

Ulbrich,  28 

United  States,  9,  32,  35.  45.  47,  5i. 

58,  61,  63,  68,  89,  97,  134,  135, 

268 

Ural  Caspian,  64 
Utah,  62,  105,  131,  133,  135,   138, 

139,  158 

VAL  DE  TRAVERS,  33,  134,  135 

Valenta,  16 

Venezuela,    10,   63,    131,    169,   225, 

281,  282 

Virginia,  44,  48,  50,  61,  105 
Virlet  d'Aoust,  38 

WADS  WORTH,  181,  185 

Warren,  39 

Waters,  278 

Wells,  272 

West  Virginia,  105 

Wheller,  102 

Wiggins,  84,  88 

Wilson,  103 

Wirth,  28 

Wolgan  Valley,  105,  107 

Wolochowitsch,  16 

Woog,  273 

Wooton,  22 

Wurtemburg,  104 

Wyoming,  32,  50,  62,  105 

YENANGYAUNG,  7 

Young,  8,  114,  117,  154,  229,  230 

ZALOZIECKI,  16 
Zanetti,  231 
Zante,  7 


Printed  in  the  United  Kingdom  by  William  Clowes  &•  Sons,  Limited  Beccles, 
for  Baillitre,  Tindall  &•  Cox. 


THIS  BOOK  IS  DUE  ON  THE  LAST  DATE 
STAMPED  BELOW 


AN     INITIAL    FINE     OF     25     CENTS 

WILL  BE  ASSESSED  FOR  FAILURE  TO  RETURN 
THIS  BOOK  ON  THE  DATE  DUE.  THE  PENALTY 
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DAY  AND  TO  $1.OO  ON  THE  SEVENTH  DAY 
OVERDUE. 


NOV    18  ' 


WOV 


1932 


QCT    271934 

DEC    4    1S34 

NOV  10  1935 

JAN  28 1937 
DEC  271937 

SEP    251931 


REC'D  LD 

MAY;  b4-c 


LD  21-50m-8,-32 


;, 

UNIVERSITY  OF  CALIFORNIA  LIBRARY 


